block: null_blk: Fix code style issues

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2083917



commit 525323d2
Author: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Date:   Wed Apr 20 09:57:15 2022 +0900

    block: null_blk: Fix code style issues

    Fix message grammar and code style issues (brackets and indentation) in
    null_init().

Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
    Link: https://lore.kernel.org/r/20220420005718.3780004-2-damien.lemoal@opensource.wdc.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>

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