Since ec13b1d6 ("blkcg: always create the blkcg_gq for the root
blkcg"), a request_list always has its blkg associated.  Drop
unnecessary rl->blkg NULL test from blk_put_rl().
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: NJens Axboe <axboe@fb.com>