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

This reverts commit 46546f28 because it
mistakenly took PMIC pinctrl/GPIO as TLMM.  The TLMM pinctrl uses "gpio"
function, but PMIC uses "normal", so original code was correct:

  msm8998-oneplus-cheeseburger.dtb: pmic@2: gpio@c000:button-backlight-state: 'oneOf' conditional failed, one must be fixed:
    'gpio' is not one of ['normal', 'paired', 'func1', 'func2', 'dtest1', 'dtest2', 'dtest3', 'dtest4', 'func3', 'func4']

Fixes: 46546f28 ("arm64: dts: qcom: msm8998-oneplus-cheeseburger: fix backlight pin function")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230312183622.460488-5-krzysztof.kozlowski@linaro.org

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

@@ -34,7 +34,7 @@ led-keypad-backlight {
 &pmi8998_gpios {
 	button_backlight_default: button-backlight-state {
 		pins = "gpio5";
-		function = "gpio";
+		function = "normal";
 		bias-pull-down;
 		qcom,drive-strength = <PMIC_GPIO_STRENGTH_NO>;
 	};