dt-bindings: mfd: Add compatible for pmx75

Add compatible for pmic pmx75 used in Snapdragon series.

Signed-off-by: Rohit Agarwal <quic_rohiagar@quicinc.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/1688395346-3126-6-git-send-email-quic_rohiagar@quicinc.com


Signed-off-by: Lee Jones <lee@kernel.org>