pinctrl: intel: Introduce common flags for GPIO mapping scheme

Few drivers are using the same flag to tell Intel pin control core
how to interpret GPIO base.

Provide a generic flags so all drivers can use.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>