libata: export host controller number thru /sys

libata: export host controller number thru /sys

As low-level drivers register their host controller(s), keep track
of the number of controllers and export thru /sys in a <host.port>
format so that udev can better match up port numbers with a
specific controller.

# pwd
/sys/devices/pci0000:00
# find . -name 'ata*' -print

(2nd controller with port multiplier attached)

./0000:00:1e.0/0000:05:01.0/ata2.7
./0000:00:1e.0/0000:05:01.0/ata2.7/link7/dev7.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.7/link7/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.0/dev7.0.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.0/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.1/dev7.1.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.1/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.2/dev7.2.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.2/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.3/dev7.3.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.3/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.4/dev7.4.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.4/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.5/dev7.5.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.5/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.6/dev7.6.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.6/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.7/dev7.7.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.7/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.8/dev7.8.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.8/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.9/dev7.9.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.9/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.7/ata_port
./0000:00:1e.0/0000:05:01.0/ata2.7/ata_port/ata2.7
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.10/dev7.10.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.10/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.11/dev7.11.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.11/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.12/dev7.12.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.12/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.13/dev7.13.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.13/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.14/dev7.14.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.7/link7.14/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.8
./0000:00:1e.0/0000:05:01.0/ata2.8/link8/dev8.0/ata_device
./0000:00:1e.0/0000:05:01.0/ata2.8/link8/ata_link
./0000:00:1e.0/0000:05:01.0/ata2.8/ata_port
./0000:00:1e.0/0000:05:01.0/ata2.8/ata_port/ata2.8

(1st controller)

./0000:00:1f.2/ata1.1
./0000:00:1f.2/ata1.1/link1/dev1.0/ata_device
./0000:00:1f.2/ata1.1/link1/ata_link
./0000:00:1f.2/ata1.1/ata_port
./0000:00:1f.2/ata1.1/ata_port/ata1.1
./0000:00:1f.2/ata1.2
./0000:00:1f.2/ata1.2/link2/dev2.0/ata_device
./0000:00:1f.2/ata1.2/link2/ata_link
./0000:00:1f.2/ata1.2/ata_port
./0000:00:1f.2/ata1.2/ata_port/ata1.2
./0000:00:1f.2/ata1.3
./0000:00:1f.2/ata1.3/link3/dev3.0/ata_device
./0000:00:1f.2/ata1.3/link3/ata_link
./0000:00:1f.2/ata1.3/ata_port
./0000:00:1f.2/ata1.3/ata_port/ata1.3
./0000:00:1f.2/ata1.4
./0000:00:1f.2/ata1.4/link4/dev4.0/ata_device
./0000:00:1f.2/ata1.4/link4/ata_link
./0000:00:1f.2/ata1.4/ata_port
./0000:00:1f.2/ata1.4/ata_port/ata1.4
./0000:00:1f.2/ata1.5
./0000:00:1f.2/ata1.5/link5/dev5.0/ata_device
./0000:00:1f.2/ata1.5/link5/ata_link
./0000:00:1f.2/ata1.5/ata_port
./0000:00:1f.2/ata1.5/ata_port/ata1.5
./0000:00:1f.2/ata1.6
./0000:00:1f.2/ata1.6/link6/dev6.0/ata_device
./0000:00:1f.2/ata1.6/link6/ata_link
./0000:00:1f.2/ata1.6/ata_port
./0000:00:1f.2/ata1.6/ata_port/ata1.6

Signed-off-by: David Milburn <dmilburn@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>