regulator: cpr3-regulator: add support for mem-acc supply corner requests

Add support for setting the corner of the mem-acc supply
regulator when the voltage of the vdd-supply regulator is scaled.
This regulator is used to select different settings for memory
internal circuitry based on the performance operating point.

Change-Id: Icf68b452ee07a13f2cf3a131b07e3952230f7519
Signed-off-by: Osvaldo Banuelos <osvaldob@codeaurora.org>