regulator: qcom-rpm: Regulator driver for the Qualcomm RPM

Driver for regulators exposed by the Resource Power Manager (RPM) found
in Qualcomm 8660, 8960 and 8064 based devices.

Signed-off-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
Signed-off-by: Mark Brown <broonie@kernel.org>