msm: pil-riva: Add support for APQ8064 regulators

AQP8064 has a different power grid than MSM8960. The Riva rail's
voltage is not longer supplied directly by a regulator, but by a
switch instead. Skip regulator voltage setting on 8064.

Change-Id: Ieb35dc10831ab0a173311ccc9dbf904497159251
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>