regulator: cpr3-regulator: add support for the ceiling interrupt

Add support for the CPR ceiling interrupt that is triggered when
hardware closed-loop attempts to increase the voltage above the
ceiling voltage.

Processor clock throttling must be disabled when this interrupt
fires so that it doesn't get stuck on indefinitely.

Change-Id: I8db8365a6041028e27fc4c1aa885b6cb94c5f6ff
Signed-off-by: David Collins <collinsd@codeaurora.org>