ARM: dts: msm: add PM8998 S12 and S13 regulators for sdm845

Add qpnp-regulator devices for PM8998 S12 and S13 regulators.
This will allow VDD_APC0 and VDD_APC1 CPR devices to directly
modify the voltage at the PMIC before CPRh and OSM are enabled.

Change-Id: I5fc8e69c0139a8ce65b6ec5c61d42e0c15721ccd
Signed-off-by: David Collins <collinsd@codeaurora.org>