ARM: dts: exynos: Replace deprecated GPIO spi-gpio properties in Universal C210

"gpio-sck" and "gpio-mosi" are deprecated so update the DTS to fix
dtbs_checks warnings like:

  arch/arm/boot/dts/exynos4210-universal_c210.dt.yaml: spi-lcd:
    gpio-sck: False schema does not allow [[85, 1, 0]]
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20200830135200.24304-14-krzk@kernel.org

arch/arm/boot/dts/exynos4210-universal_c210.dts

@@ -124,8 +124,8 @@ spi-3 {
 		#address-cells = <1>;
 		#size-cells = <0>;
 
-		gpio-sck = <&gpy3 1 GPIO_ACTIVE_HIGH>;
-		gpio-mosi = <&gpy3 3 GPIO_ACTIVE_HIGH>;
+		sck-gpios = <&gpy3 1 GPIO_ACTIVE_HIGH>;
+		mosi-gpios = <&gpy3 3 GPIO_ACTIVE_HIGH>;
 		num-chipselects = <1>;
 		cs-gpios = <&gpy4 3 GPIO_ACTIVE_LOW>;