can: raw: reorder struct uniqframe's members to optimise packing

struct uniqframe has one hole. Reorder the fields to save 8 bytes.

Statistics before:

  $ pahole --class_name=uniqframe net/can/raw.o
  struct uniqframe {
  	int                        skbcnt;               /*     0     4 */

  	/* XXX 4 bytes hole, try to pack */

  	const struct sk_buff  *    skb;                  /*     8     8 */
  	unsigned int               join_rx_count;        /*    16     4 */

  	/* size: 24, cachelines: 1, members: 3 */
  	/* sum members: 16, holes: 1, sum holes: 4 */
  	/* padding: 4 */
  	/* last cacheline: 24 bytes */
  };

...and after:

  $ pahole --class_name=uniqframe net/can/raw.o
  struct uniqframe {
  	const struct sk_buff  *    skb;                  /*     0     8 */
  	int                        skbcnt;               /*     8     4 */
  	unsigned int               join_rx_count;        /*    12     4 */

  	/* size: 16, cachelines: 1, members: 3 */
  	/* last cacheline: 16 bytes */
  };

Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Vincent Mailhol <mailhol@kernel.org>
Link: https://patch.msgid.link/20250917-can-raw-repack-v2-1-395e8b3a4437@kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Author: vincent-mailhol

net/can/raw.c

@@ -75,8 +75,8 @@ MODULE_ALIAS("can-proto-1");
  */
 
 struct uniqframe {
-	int skbcnt;
 	const struct sk_buff *skb;
+	int skbcnt;
 	unsigned int join_rx_count;
 };