MIPS: Alchemy: abstract USB block control register access

MIPS: Alchemy: abstract USB block control register access

Alchemy chips have one or more registers which control access
to the usb blocks as well as PHY configuration.  I don't want
the OHCI/EHCI glues to know about the different registers and bits;
new code hides the gory details of USB configuration from them.

Signed-off-by: Manuel Lauss <manuel.lauss@googlemail.com>
To: Linux-MIPS <linux-mips@linux-mips.org>
Cc: linux-usb@vger.kernel.org
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Patchwork: https://patchwork.linux-mips.org/patch/2709/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>