gpio/lynxpoint: add chipset gpio driver.

Add gpio support for Intel Lynxpoint chipset.

Lynxpoint supports 94 gpio pins which can generate interrupts.
Driver will fail requests for pins that are marked as owned by ACPI, or
set in an alternate mode (non-gpio).

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>