[SCSI] qla2xxx: Consolidate queuecommand implementations.

Post refactoring/multi-queue additions essentially eliminated the
need for separate ISP24XX+ queuecommand as isp_ops contains a
function pointer to the associated 'start_scsi()' operation.

Signed-off-by: Giridhar Malavali <giridhar.malavali@qlogic.com>
Signed-off-by: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>