[SCSI] qla2xxx: Obtain loopback iteration count from bsg request.

qla2x00_loopback_test() was hard setting the loopback iteration
count to 1 rather than obtaining it from the bsg request.

Signed-off-by: Joe Carnuccio <joe.carnuccio@qlogic.com>
Signed-off-by: Saurav Kashyap <saurav.kashyap@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>