ARM: dts: imx6q: Add spi4 alias

The quad version has a SPI controller more than the other
versions. Add an alias for it.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/imx6q.dtsi

@@ -13,6 +13,10 @@
 #include "imx6qdl.dtsi"
 
 / {
+	aliases {
+		spi4 = &ecspi5;
+	};
+
 	cpus {
 		#address-cells = <1>;
 		#size-cells = <0>;