pinctrl: intel: fix offset calculation issue of register PAD_OWN

The calculation equation of PAD_OWN register offset is not
correct for Broxton, verified this fix will get right
offset for Broxton.

Signed-off-by: Qi Zheng <qi.zheng@intel.com>
Signed-off-by: Qipeng Zha <qipeng.zha@intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>