[SCSI] libsas: fix runaway error handler problem

libsas makes use of scsi_schedule_eh() but forgets to clear the
host_eh_scheduled flag in its error handling routine.  Because of this,
the error handler thread never gets to sleep; it's constantly awake and
trying to run the error routine leading to console spew and inability to
run anything else (at least on a UP system).  The fix is to clear the
flag as we splice the work queue.

Cc: stable@kernel.org
Signed-off-by: James Bottomley <James.Bottomley@suse.de>