ext4: call ext4_mb_mark_context in ext4_mb_clear_bb

Call ext4_mb_mark_context in ext4_mb_clear_bb to remove repeat code.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230928160407.142069-8-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>