linux-phytec-ti

ext4: fix an incorrect comment about i_mutex

i_mutex is not held when ->sync_file is called.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>