[SCSI] bnx2fc: host stats show the link speed 'unknown' on NIC partitioned interfaces

NIC partitioned interfaces reports the speed of 2500 which was not handled by
the driver.

Signed-off-by: Bhanu Prakash Gollapudi <bprakash@broadcom.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>