ext4: drop ext4_es_is_delonly()

Since we don't add delayed flag in unwritten extents, so there is no
difference between ext4_es_is_delayed() and ext4_es_is_delonly(),
just drop ext4_es_is_delonly().

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20240813123452.2824659-12-yi.zhang@huaweicloud.com


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