udf: Drop udf_sync_inode()

udf: Drop udf_sync_inode()

The only place using udf_sync_inode() is now inode_getblk() for flushing
IS_SYNC inodes after write and page_mkwrite allocating blocks. For write
the flushing is actually taken care of by generic_write_sync() so it
isn't needed here. For page_mkwrite it does have effect however none of
the other filesystems seem to bother with flushing IS_SYNC inode on page
fault and properly synchronizing such writeback with standard inode
writeback would be slightly complex due to locking constraints. So just
drop IS_SYNC inode handling from inode_getblk().

Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20260727104923.3828017-32-jack@suse.cz
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>