ARM: dts: msm8974: castor: Define pm8841 regulators

Define the pm8841 regulators under SMD/RPM, to allow the modem
remoteproc to set the voltage during boot of the remote processor.

Entries are just copied from the Honami dts.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221121212226.321514-1-luca@z3ntu.xyz