msm: rpm-regulator: Add support for new voltage corner RPM regulator type

Add support in the rpm-regulator driver for the new voltage corner
RPM regulator resource type.  Resources of this type allow for
consumers to request a voltage corner in low, nominal, and high
range instead of using a discrete voltage value.  This is useful
for rails whose voltage can be tuned based on the speed inherent
in the silicon of the specific chip that is being run on.

Also rename vreg_enable and vreg_disable functions to avoid check
patch warnings.

Change-Id: I32f5d13565ca777f9a49adbcfde297dfe3b11197
Signed-off-by: David Collins <collinsd@codeaurora.org>
3 files changed