bnx2x: Read FIP mac from SHMEM in single function mode

Read FIP MAC address from SHMEM's "port" section
similar to what we do in a MF mode when we read it from
a "func" section of SHMEM.

Signed-off-by: Vladislav Zolotarov <vladz@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>