arm64: dts: qcom: pmi8994: add missing MPP compatible fallback

Bindings require usage of generic MPP fallback in compatible:

  qcom/apq8094-sony-xperia-kitakami-karin_windy.dtb: pmic@2: mpps@a000:compatible: ['qcom,pmi8994-mpp'] is too short
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220908081050.29751-1-krzysztof.kozlowski@linaro.org

arch/arm64/boot/dts/qcom/pmi8994.dtsi

@@ -21,7 +21,7 @@ pmi8994_gpios: gpios@c000 {
 		};
 
 		pmi8994_mpps: mpps@a000 {
-			compatible = "qcom,pmi8994-mpp";
+			compatible = "qcom,pmi8994-mpp", "qcom,spmi-mpp";
 			reg = <0xa000>;
 			gpio-controller;
 			gpio-ranges = <&pmi8994_mpps 0 0 4>;