ramips: fix Omega2 compatible string

Change the compatibel from Omega to Omega2 and add the compatible string
where missing.

Signed-off-by: Mathias Kresin <dev@kresin.me>

target/linux/ramips/dts/OMEGA2.dts

@@ -3,6 +3,7 @@
 #include "OMEGA2.dtsi"
 
 / {
+	compatible = "onion,omega2", "mediatek,mt7628an-soc";
 	model = "Onion Omega2";
 
 	memory@0 {

target/linux/ramips/dts/OMEGA2.dtsi

@@ -4,7 +4,7 @@
 #include <dt-bindings/input/input.h>
 
 / {
-	compatible = "onion,omega", "mediatek,mt7628an-soc";
+	compatible = "onion,omega2", "mediatek,mt7628an-soc";
 
 	chosen {
 		bootargs = "console=ttyS0,115200";

target/linux/ramips/dts/OMEGA2P.dts

@@ -3,6 +3,7 @@
 #include "OMEGA2.dtsi"
 
 / {
+	compatible = "onion,omega2p", "onion,omega2", "mediatek,mt7628an-soc";
 	model = "Onion Omega2+";
 
 	memory@0 {