gpiolib: Don't free if pin ranges are not defined

A similar check was added in gpiochip_generic_request, but not in free.
This has caused an imbalance count of request vs. free calls to the
pinctrl driver. This patch is targeted to fix that issue.

Fixes: 2ab73c6d ("gpio: Support GPIO controllers without pin-ranges")
Signed-off-by: Edmond Chung <edmondchung@google.com>
Signed-off-by: Andrew Chant <achant@google.com>
Signed-off-by: Will McVicker <willmcvicker@google.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>