ARM: dts: Add SPI CS on exynos5250-snow

Although there is only one choice of chipselect it is necessary to
specify it. The driver cannot claim the gpio otherwise.

Signed-off-by: Michal Suchanek <hramrach@gmail.com>
Acked-by: Javier Martinez Canillas <javier@osg.samsung.com>
Acked-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>

arch/arm/boot/dts/exynos5250-snow.dts

@@ -692,6 +692,7 @@
 	status = "okay";
 	samsung,spi-src-clk = <0>;
 	num-cs = <1>;
+	cs-gpios = <&gpa2 5 GPIO_ACTIVE_HIGH>;
 };
 
 &usbdrd_dwc3 {