board: rockchip: Correct i2c2 pinctrl for RGxx3

The pinctrl on the Anbernic RGxx3 for the i2c2 bus does not use the
default value, so explicitly define it.

Fixes: 6cf6fe2537 ("board: rockchip: add Anbernic RGXX3 Series Devices")
Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>

arch/arm/dts/rk3566-anbernic-rgxx3-u-boot.dtsi

@@ -47,6 +47,8 @@
 };
 
 &i2c2 {
+	pinctrl-0 = <&i2c2m1_xfer>;
+	pinctrl-names = "default";
 	status = "okay";
 };