ext4: fix the comment of ext4_map_blocks()/ext4_ext_map_blocks()

this comment of ext4_map_blocks()/ext4_ext_map_blocks() need
update after commit c2177057("ext4: Define a new set of
flags for ext4_get_blocks()").

Signed-off-by: Cheng Nie <niecheng1@uniontech.com>
Link: https://lore.kernel.org/r/20240118062511.28276-1-niecheng1@uniontech.com


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