mfd: intel_soc_pmic: Add support for Broxton WC PMIC

IRQ control registers of Intel Broxton Whisky Cove PMIC are
separated in two parts, so add secondary IRQ chip.
And the new member of device will be used in PMC IPC regmap APIs.

Signed-off-by: Qipeng Zha <qipeng.zha@intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>