[media] drivers: media: usb: b2c2: use usb_*_coherent() instead of pci_*_consistent() in flexcop-usb.c

Some architectures do not support PCI, but still support USB, so need
let our usb driver try to use usb_* instead of pci_* to support these
architectures, or can not pass compiling.
The related error (with allmodconfig for arc):
    CC [M]  drivers/media/usb/b2c2/flexcop-usb.o
  drivers/media/usb/b2c2/flexcop-usb.c: In function ‘flexcop_usb_transfer_exit’:
  drivers/media/usb/b2c2/flexcop-usb.c:393: error: implicit declaration of function ‘pci_free_consistent’
  drivers/media/usb/b2c2/flexcop-usb.c: In function ‘flexcop_usb_transfer_init’:
  drivers/media/usb/b2c2/flexcop-usb.c:410: error: implicit declaration of function ‘pci_alloc_consistent’
Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>