bnx2x: Obtain Bus Device Function from register

bnx2x: Obtain Bus Device Function from register

BDF was obtained from kernel but since in virtualized environment
(e.g. physical device assigment in KVM) the function number may
not be the real one, the info must be obtained from the device.

(cherry picked from commit c22610d0001ebf3420d39f419056a56c5aa43096)
Signed-off-by: Ariel Elior <ariele@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Joe Jin <joe.jin@oracle.com>