ext4: set extents flag when migrating file to use extents

Fix a typo that was introduced in commit 07a03824 (in 2.6.36) which
caused the extents flag not to be set at the conclusion of converting
an inode to use extents.
Reported-by: NPeter Uchno <peter.uchno@gmail.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/migrate.c

@@ -376,7 +376,7 @@ static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
 	 * We have the extent map build with the tmp inode.
 	 * Now copy the i_data across
 	 */
-	ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS);
+	ext4_set_inode_flag(inode, EXT4_INODE_EXTENTS);
 	memcpy(ei->i_data, tmp_ei->i_data, sizeof(ei->i_data));
 
 	/*