regulator: cprh-kbss-regulator: add support for APM crossover corner

Add support for a corner whose open-loop voltage corresponds to the
VDD supply voltage required during an APM switch transition. This
corner is requested by OSM hardware to the CPRh controller when
the VDD supply must be set to a specific voltage to ensure a stable
APM switch procedure. Define a crossover corner of 880 mV for both
VDD_APC CPR devices.

CRs-Fixed: 1021656
Change-Id: Icf4b640ec2c330b0d9721d3494297e2d8445c9b6
Signed-off-by: Osvaldo Banuelos <osvaldob@codeaurora.org>