ARM: dts: msm: Add VDD_APCC mem-acc regulator devices for msm8996

Add a mem-acc supply regulator to the VDD_APCC CPR3 controller
device node and two additional mem-acc supplies, one per cluster,
to enable control of memory acc settings when the VDD_APCC supply
is scaled. Define the appropriate mem-acc voltage threshold
so that mem-acc requests take place when the VDD supply or LDO
regulator set point cross that voltage.

Change-Id: If70f67c7d4527ff8824006ca6f31d1506e6aa722
Signed-off-by: Osvaldo Banuelos <osvaldob@codeaurora.org>