pinctrl: baytrail: Rectify debounce support

The commit 658b476c ("pinctrl: baytrail: Add debounce configuration")
implements debounce for Baytrail pin control, but seems wasn't tested properly.

The register which keeps debounce value is separated from the configuration
one. Writing wrong values to the latter will guarantee wrong behaviour of the
driver and even might break something physically.

Besides above there is missed case how to disable it, which is actually done
through the bit in configuration register.

Rectify implementation here by using proper register for debounce value.

Fixes: 658b476c ("pinctrl: baytrail: Add debounce configuration")
Cc: Cristina Ciocan <cristina.ciocan@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>