msm: krait-regulator: Add support for PMIC regulator phase scaling factor

Add support to read an eFuse which specifies the appropriate PMIC
regulator phase scaling factor to apply for a given chip.  Using
the phase scaling factor reduces power consumption in certain
cases.

Also specify the phase scaling factor eFuse address for MSM8974
since this property value is made to be required.

Change-Id: I77a480a77e890f044f18fdfd002ec183d75347d0
Signed-off-by: David Collins <collinsd@codeaurora.org>