arm64: dts: qcom: msm8998-oneplus-cheeseburger: fix backlight pin function

There is no "normal" function, so use "gpio" for backlight button pin
configuration.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221013210612.95994-2-krzysztof.kozlowski@linaro.org

arch/arm64/boot/dts/qcom/msm8998-oneplus-cheeseburger.dts

@@ -35,7 +35,7 @@ &pmi8998_gpio {
 	button_backlight_default: button-backlight-state {
 		pinconf {
 			pins = "gpio5";
-			function = "normal";
+			function = "gpio";
 			bias-pull-down;
 			qcom,drive-strength = <PMIC_GPIO_STRENGTH_NO>;
 		};