Revert "scsi: check request was requeued before scheduling requeue work"

This reverts change I5de4cb0df00aa0c5dc66a4faad71fa04446f6545.

Disabling requeueing of a completed request will cause a request
not to be retried (by requeueing it) in cases where the low-level
driver detected some error but finished processing of the requeust.
Specifically, not retrying the request will cause calls to functions
such as blk_execute_rq to block forever.

Change-Id: Ic1e96bb4996afa05f7d9bde3167d1400a174b737
Signed-off-by: Gilad Broner <gbroner@codeaurora.org>