kernel: 6.1: fix swconfig not working

On 6.1 swconfig is not showing up and there's a splat:

| ------------[ cut here ]------------
| WARNING: CPU: 0 PID: 1 at genl_register_family+0xb4/0x81c
| Modules linked in:
| CPU: 0 PID: 1 Comm: swapper Not tainted 6.1.29 #0
| Hardware name: Netgear WNDR4700/WNDR4720 Series APM821XX [...]
| NIP:  c0599370 LR: c0599344 CTR: c08c9950
| REGS: c0c21cb0 TRAP: 0700   Not tainted  (6.1.29)
| MSR:  00029000 <CE,EE,ME>  CR: 48000888  XER: 00000000
|
| GPR00: c0002678 c0c21da0 c0c2cd80 [...]
| NIP [c0599370] genl_register_family+0xb4/0x81c
| LR [c0599344] genl_register_family+0x88/0x81c
| Call Trace:
| [c0c21d80] [c0c21df4] 0xc0c21df4 (unreliable)
| [c0c21e10] [c08c9988] swconfig_init+0x38/0x64
| [c0c21e30] [c0002678] do_one_initcall+0x50/0x260

This is due to it failing to register the netlink
family since changes to upstream linux in patch.

| commit 9c5d03d362519f36cd551aec596388f895c93d2d
|Author: Jakub Kicinski <[email protected]>
|Date:   Wed Aug 24 17:18:30 2022 -0700
|
|   genetlink: start to validate reserved header byte

this is fixed by adding the proper value to the introduced
"resv_start_op" parameter.

Signed-off-by: Christian Lamparter <[email protected]>

target/linux/generic/files/drivers/net/phy/swconfig.c

@@ -1054,6 +1054,9 @@ static struct genl_family switch_fam = {
 	.module = THIS_MODULE,
 	.ops = swconfig_ops,
 	.n_ops = ARRAY_SIZE(swconfig_ops),
+#if LINUX_VERSION_CODE > KERNEL_VERSION(6,0,0)
+	.resv_start_op = SWITCH_CMD_SET_VLAN + 1,
+#endif
 };
 
 #ifdef CONFIG_OF