m68k: dts: add i2c nodes

Add all the i2c nodes for each family, and add specific i2c
overwrites in the related board-specific dts.

Signed-off-by: Angelo Dureghello <angelo@kernel-space.org>
diff --git a/arch/m68k/dts/stmark2.dts b/arch/m68k/dts/stmark2.dts
index ebe8580..3ba68b7 100644
--- a/arch/m68k/dts/stmark2.dts
+++ b/arch/m68k/dts/stmark2.dts
@@ -41,3 +41,7 @@
 	status = "okay";
 	mii-base = <0>;
 };
+
+&i2c0 {
+	status = "okay";
+};