ext4: fix ext4_mb_clear_bb() kernel-doc comment

Remove the excess description of @bh in ext4_mb_clear_bb() kernel-doc
comment to remove warnings found by running scripts/kernel-doc, which
is caused by using 'make W=1'.

fs/ext4/mballoc.c:5895: warning: Excess function parameter 'bh'
description in 'ext4_mb_clear_bb'

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220301092136.34764-1-yang.lee@linux.alibaba.com


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