regulator: dt-bindings: qcom,rpmh: Add PM7550 compatible

Add the PM7550 compatible for the regulators in the PMIC found with the
Milos SoC.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Luca Weiss <luca.weiss@fairphone.com>
Link: https://patch.msgid.link/20250711-pm7550-pmr735b-rpmh-regs-v2-1-bca8cc15c199@fairphone.com


Signed-off-by: Mark Brown <broonie@kernel.org>