pinctrl: baytrail: fix some error handling in debugfs

We need to unlock before continuing.  Also the continue was accidentally
left out on one error path which would lead to a NULL dereference.

Fixes: 86e3ef81 ('pinctrl: baytrail: Update gpio chip operations')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>