jbd2: clean up misleading comments for jbd2_fc_release_bufs

This comments was for jbd2_fc_wait_bufs, not for jbd2_fc_release_bufs.
Remove this misleading comments.

Signed-off-by: yangerkun <yangerkun@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210608141236.459441-1-yangerkun@huawei.com


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