ARM: dts: imx6ull: Fix i.MX6ULL/ULZ ocotp compatible

Since imx6ulz.dtsi includes imx6ull.dtsi, we only need to fix the compatible
string here to achieve the correct OTP size for both SoCs.
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx6ull.dtsi

@@ -30,6 +30,10 @@ &cpu0 {
 	>;
 };
 
+&ocotp {
+	compatible = "fsl,imx6ull-ocotp", "syscon";
+};
+
 / {
 	soc {
 		aips3: aips-bus@2200000 {