thermal: add Intel BXT WhiskeyCove PMIC thermal driver

This change adds support for Intel BXT Whiskey Cove PMIC thermal
driver which is intended to handle the alert interrupts triggered
upon thermal trip point cross and notify the thermal framework
appropriately with the zone, temp, crossed trip and event details.

Signed-off-by: Yegnesh S Iyer <yegnesh.s.iyer@intel.com>
Signed-off-by: Bin Gao <bin.gao@intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>