dt-bindings: mfd: qcom,spmi-pmic: Add compatible for pmm8654au

PMM8654au is the SPMI PMIC variant used on sa8775p-ride. Add a compatible
for it.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230314183043.619997-5-brgl@bgdev.pl