[SCSI] bnx2fc: Tx/Rx byte counts reset to 0 when exceeding 32 bit values

Since the FW counters are 32-bit, accumulate the stats in the driver.

[jejb: fix checkpatch warning]
Signed-off-by: Bhanu Prakash Gollapudi <bprakash@broadcom.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>