regulator: qcom_spmi: Add PM8909 regulators

Add the necessary definitions for the PM8909 PMIC to the
qcom_spmi-regulator driver to allow reading the actual voltages applied
to the hardware at runtime. This is mainly intended for debugging since
the regulators are usually controlled through the RPM firmware (via
qcom_smd-regulator).

Signed-off-by: Stephan Gerhold <stephan.gerhold@kernkonzept.com>
Link: https://lore.kernel.org/r/20230912-spmi-pm8909-v1-2-ba4b3bfaf87d@gerhold.net


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