regulator: qcom_smd: Document PM6125 PMIC

Document the pm6125 compatible string and available regulators in the QCom
SMD RPM regulator documentation.

Signed-off-by: Adam Skladowski <a39.skl@gmail.com>
Signed-off-by: Iskren Chernev <iskren.chernev@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220802221112.2280686-5-iskren.chernev@gmail.com


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