arm64: dts: qcom: sm8250-pdx203: add required pin function

DT bindings expect function in each pin state in the pin configuration:

  sm8250-sony-xperia-edo-pdx203.dtb: pinctrl@f100000: cam-pwr-b-state: 'oneOf' conditional failed, one must be fixed:
    'function' is a required property
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230717210055.21979-2-krzysztof.kozlowski@linaro.orgSigned-off-by: Bjorn Andersson <andersson@kernel.org>

arch/arm64/boot/dts/qcom/sm8250-sony-xperia-edo-pdx203.dts

@@ -366,6 +366,7 @@ &tlmm {
 
 	cam_pwr_b_cs: cam-pwr-b-state {
 		pins = "gpio69";
+		function = "gpio";
 		drive-strength = <2>;
 		bias-disable;
 		output-low;
@@ -373,6 +374,7 @@ cam_pwr_b_cs: cam-pwr-b-state {
 
 	cam_pwr_a_cs: cam-pwr-a-state {
 		pins = "gpio71";
+		function = "gpio";
 		drive-strength = <2>;
 		bias-disable;
 		output-low;