ramips: mt7621-dts: add pinctrl properties for ethernet

Add the missing pinctrl properties on the ethernet node.
GMAC1 will start working with this change.

Link: https://lore.kernel.org/netdev/83a35aa3-6cb8-2bc4-2ff4-64278bbcd8c8@arinc9.com/

Overwrite pinctrl-0 property without rgmii2_pins on devicetrees which use
the rgmii2 pins as GPIO (22 - 33).

Give gpio function to rgmii2 pin group on mt7621_tplink_archer-x6-v3.dtsi
which uses GPIO 28.

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>

target/linux/ramips/dts/mt7621_mikrotik_routerboard-m11g.dts

@@ -66,6 +66,10 @@
 	};
 };
 
+&ethernet {
+	pinctrl-0 = <&mdio_pins>, <&rgmii1_pins>;
+};
+
 &switch0 {
 	ports {
 		port@0 {