pci: pci-sysfs.c needs export.h for THIS_MODULE

pci: pci-sysfs.c needs export.h for THIS_MODULE

Otherwise, once you break the chain of implicit includes from
device.h --> module.h then you will get this:

pci-sysfs.c: In function ‘remove_store’:
pci-sysfs.c:350: error: ‘THIS_MODULE’ undeclared (first use in this function)
pci-sysfs.c:350: error: (Each undeclared identifier is reported only once
pci-sysfs.c:350: error: for each function it appears in.)
make[3]: *** [drivers/pci/pci-sysfs.o] Error 1

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>