ext4: remove unneeded return value of ext4_mb_release_context

Function ext4_mb_release_context always return 0 and the return value is
never used. Just remove unneeded return value of ext4_mb_release_context.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240105092102.496631-4-shikemeng@huaweicloud.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>