cnic: Use pfid for internal memory offsets.

The pfid (physical function ID) is the same as PCI function on production
devices.  The pfid for future devices will be different and will be used
for internal memory offsets.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>