dt-bindings: media: s5c73m3: Fix reset-gpio descriptor

The reset-gpios is described as xshutdown-gpios on the required
properties, as it is on the driver. Despite that, the device tree
example set the property 'reset-gpios' instead of the property
'xshutdown-gpios'.

Therefore, this patch updates the example to match the property specified
on the driver.
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

Documentation/devicetree/bindings/media/samsung-s5c73m3.txt

@@ -76,7 +76,7 @@ i2c@138a000000 {
 		clock-frequency = <24000000>;
 		clocks = <&clk 0>;
 		clock-names = "cis_extclk";
-		reset-gpios = <&gpf1 3 1>;
+		xshutdown-gpios = <&gpf1 3 1>;
 		standby-gpios = <&gpm0 1 1>;
 		port {
 			s5c73m3_ep: endpoint {