scsi: qla2xxx: Add ability to autodetect SFP type

SFP can come in 2 formats: short range/SR and long range/LR.  For LR,
user the can increase the number of Buffer to Buffer credits between end
points via Cavium's command line tool.  By default, FW uses a lower BB
Credit value optimized for SR.  This patch will read the SFP for each
link up event and during chip reset sequence. If the SFP type and
setting are mismatch, then the chip is reset 1 time to use the
appropriate setting.

Signed-off-by: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>