pinctrl: intel: Add support for 1k additional pull-down

The next generation Intel GPIO hardware supports additional 1k pull-down
per-pad. Add support for this to the Intel core pinctrl driver.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>