ARM: dts: rmobile: Extract i2c6 on M2W Porter

The i2c6 node is missing in mainline Linux thus far, pull it
into U-Boot specific DT until it hits mainline Linux, to make
syncing of DTs easier.
Signed-off-by: NMarek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
---
V2: Rebase on u-boot/master

arch/arm/dts/r8a7791-porter-u-boot.dts

@@ -11,3 +11,8 @@
 &scif0 {
 	u-boot,dm-pre-reloc;
 };
+
+&i2c6 {
+	status = "okay";
+	clock-frequency = <400000>;
+};

arch/arm/dts/r8a7791-porter.dts

@@ -372,11 +372,6 @@
 	clock-frequency = <400000>;
 };
 
-&i2c6 {
-	status = "okay";
-	clock-frequency = <400000>;
-};
-
 &sata0 {
 	status = "okay";
 };