regulator: cpr-regulator: add support for clamp timer interval control

Update the cpr-regulator driver so that the clamp timer interval
register parameter can be configured for a given cpr-regulator
device via the qcom,cpr-clamp-timer-interval device tree
property.  The clamp timer interval defines a delay to wait with
the CPR controller loop disabled after the CPU clamp signal
changes or a new sensor bypass or mask register value is written.

A non-zero clamp timer interval value can be used to handle
resetting CPR sensors that are disabled on processors that make
use of BHS type switches for power collapsing.

A side effect of using a non-zero clamp timer interval value is
that software will not be able to determine the error or
error_steps values associated with a given CPR up or down
recommendation.

Change-Id: Ied5d689848d042ee60488f5001b0ca267627497a
CRs-Fixed: 687809
Signed-off-by: David Collins <collinsd@codeaurora.org>