pinctrl: intel: Use helper to restore register values on ->resume()

We can restore only values that had been changed and do not spam kernel log
with unnecessary messages. Convert intel_gpio_update_pad_mode() to a helper
function that will be used across few callers.

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