statx: Update offset commentary for struct statx

In commit 2a82bb0294 ("statx: stx_subvol"), a new member was added to
struct statx, but the offset comment was not correct. Update it.

Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20240529081725.3769290-1-john.g.garry@oracle.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

include/uapi/linux/stat.h

@@ -126,8 +126,8 @@ struct statx {
 	__u64	stx_mnt_id;
 	__u32	stx_dio_mem_align;	/* Memory buffer alignment for direct I/O */
 	__u32	stx_dio_offset_align;	/* File offset alignment for direct I/O */
-	__u64	stx_subvol;	/* Subvolume identifier */
 	/* 0xa0 */
+	__u64	stx_subvol;	/* Subvolume identifier */
 	__u64	__spare3[11];	/* Spare space for future expansion */
 	/* 0x100 */
 };