fs: Mark function as static in ext3/dir.c

Mark function as static in ext3/dir.c because it is not used outside
this file.

This also eliminates the following warning in ext3/dir.c:
fs/ext3/dir.c:278:8: warning: no previous prototype for ‘ext3_dir_llseek’ [-Wmissing-prototypes]
Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/ext3/dir.c

@@ -275,7 +275,7 @@ static inline loff_t ext3_get_htree_eof(struct file *filp)
  * NOTE: offsets obtained *before* ext3_set_inode_flag(dir, EXT3_INODE_INDEX)
  *       will be invalid once the directory was converted into a dx directory
  */
-loff_t ext3_dir_llseek(struct file *file, loff_t offset, int whence)
+static loff_t ext3_dir_llseek(struct file *file, loff_t offset, int whence)
 {
 	struct inode *inode = file->f_mapping->host;
 	int dx_dir = is_dx_dir(inode);