pinctrl: baytrail: Avoid clearing debounce value when turning it off

Baytrail pin control has a common register to set up debounce timeout.
When a pin configuration requested debounce to be disabled, the rest
of the pins may still want to have debounce enabled and thus rely on
the common timeout value. Avoid clearing debounce value when turning
it off for one pin while others may still use it.

Fixes: 658b476c ("pinctrl: baytrail: Add debounce configuration")
Depends-on: 04ff5a09 ("pinctrl: baytrail: Rectify debounce support")
Depends-on: 827e1579 ("pinctrl: baytrail: Rectify debounce support (part 2)")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>