pinctrl: intel: unlock on error in intel_config_set_pull()

We need to unlock before returning -EINVAL on this error path.

Fixes: 04cc058f ("pinctrl: intel: Add support for 1k additional pull-down")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>