ext4: Simplify handling of journalled data in ext4_bmap()

Now that ext4_writepages() gets journalled data into its final location
we just use filemap_write_and_wait() instead of special handling of
journalled data in ext4_bmap(). We can also drop EXT4_STATE_JDATA flag
as it is not used anymore.

Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230329154950.19720-11-jack@suse.cz


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