Some newer Atom CPUs, eg Avoton and Bay Trail, use slightly different
register layouts for the iTCO than the current v1 and v2 iTCO.
Differences from previous iTCO versions include:
- The ACPI space is enabled in the "ACPI base address" register instead
  of the "ACPI control register"

- The "no reboot" functionality is set in the "Power Management
  Configuration" register instead of the "General Control and Status"
  (GCS) register or PCI configuration space.

- The "ACPI Control Register" is not present on v3.  The "Power
  Management Configuration Base Address" register resides at the same
  address is Avoton/Bay Trail.

To differentiate these newer chipsets create a new v3 iTCO version and
update the MFD driver to support them.
Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
Tested-by: Rajat Jain <rajatjain@juniper.net>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>