ramips: 6.1: pinctrl: fix compilation with 6.1

Upstream changed in ed5c2f5fd10d ("i2c: Make remove callback return void")
the i2c driver's remove function to return no value. Adapt the driver code
to compile with 5.15 and 6.1 like it is done in other projects [0].

Fixes errors in the form of:
  make[8]: Leaving directory '/home/nick/openwrt/build_dir/target-mipsel_24kc_musl/linux-ramips_mt7621/linux-6.1.29'
    CC      drivers/pinctrl/pinctrl-aw9523.o
  drivers/pinctrl/pinctrl-aw9523.c:1117:19: error: initialization of 'void (*)(struct i2c_client *)' from incompatible pointer type 'int (*)(struct i2c_client *)' [-Werror=incompatible-pointer-types]
 1117 |         .remove = aw9523_remove,
      |                   ^~~~~~~~~~~~~
  drivers/pinctrl/pinctrl-aw9523.c:1117:19: note: (near initialization for 'aw9523_driver.remove')
  cc1: all warnings being treated as errors

[0] - https://gitlab.com/ddcci-driver-linux/ddcci-driver-linux/-/merge_requests/10/diffs

Signed-off-by: Nick Hainke <[email protected]>

target/linux/ramips/files/drivers/pinctrl/pinctrl-aw9523.c

@@ -1097,6 +1097,13 @@ static int aw9523_remove(struct i2c_client *client)
 	return 0;
 }
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 1, 0)
+static void aw9523_remove_void(struct i2c_client *client)
+{
+	aw9523_remove(client);
+}
+#endif
+
 static const struct i2c_device_id aw9523_i2c_id_table[] = {
 	{ "aw9523_i2c", 0 },
 	{ }
@@ -1114,7 +1121,11 @@ static struct i2c_driver aw9523_driver = {
 		.of_match_table = of_aw9523_i2c_match,
 	},
 	.probe = aw9523_probe,
+	#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 1, 0)
+	.remove = aw9523_remove_void,
+	#else
 	.remove = aw9523_remove,
+	#endif
 	.id_table = aw9523_i2c_id_table,
 };
 module_i2c_driver(aw9523_driver);