platform/x86: Add support for Dollar Cove TI power button

This provides a new input driver for supporting the power button on
Dollar Cove TI PMIC, found on Cherrytrail-based devices.
The patch is based on the original work by Intel, found at:
  https://github.com/01org/ProductionKernelQuilts

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=193891


Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>