The optional variants for the gpiod_get() family of functions return NULL
if the GPIO in question is not associated with this device. They return
ERR_PTR() on any other error. NULL descriptors are graciously handled by
GPIOLIB and can be safely passed to any of the GPIO consumer interfaces
as they will return 0 and act as if the function succeeded. If one is
using the optional variant, then there's no point in checking for NULL.

Fixes: 68456671 ("Bluetooth: hci_qca: Fix NULL vs IS_ERR_OR_NULL check in qca_serdev_probe")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>