block: change flush sequence list addition back to front add
block: change flush sequence list addition back to front add

Commit 18741986 inadvertently changed the rq flush insertion
from a head to a tail insertion. Fix that back up.

Signed-off-by: Mike Snitzer <7e9daf5b000ddeb0e79f2f4aa44d46c81fd4f561@redhat.com>
Signed-off-by: Jens Axboe <cd8c6775e60d6f67a6984377324e5290df3d5358@fb.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs