logfs: no need to lock directory in lseek

Signed-off-by: Al Viro <[e-mail]>

fs/logfs/dir.c

···
 	.unlocked_ioctl	= logfs_ioctl,
 	.iterate_shared	= logfs_readdir,
 	.read		= generic_read_dir,
-	.llseek		= default_llseek,
+	.llseek		= generic_file_llseek,
 };