ARM: dts: msm: Use corner voting for VDD_MX for 8916

Currently, APPS requests for absolute voltages on VDD_MX.
For any change in these absolute values there is a hard
dependency on RPM and APPS. Move to a corner based voting
scheme (for l3_ao and l3_so regulators) to avoid this
dependency and allow RPM to select the right voltage specific
to a corner.

For the existing clients the default 'pm8916-l3' regulator
continues supporting uV based requests. Keep the min-uV
for this regulator at the least value to allow RPM to apply
a fuse based vdd-min.

Also, Update the CPR MX corner map with the required corner values.

Change-Id: I6263b1b4ebc293dc22bc6f4a4244b0545586726c
Signed-off-by: Tirupathi Reddy <tirupath@codeaurora.org>
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>