ARM: dts: qcom: pmx65: add fallback compatible to PMIC GPIO

The bindings require all PMIC GPIO nodes to have two compatibles -
specific followed by SPMI or SSBI fallback.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220507194913.261121-12-krzysztof.kozlowski@linaro.org