linux-imx

block: fix checking return value of blk_mq_init_queue

Check IS_ERR_OR_NULL(return value) instead of just return value.

Signed-off-by: Ming Lei <ming.lei@canonical.com>

Reduced to IS_ERR() by me, we never return NULL.
Signed-off-by: Jens Axboe <axboe@fb.com>