Bluetooth: hci_intel: Fix null gpio desc pointer dereference

gpiod_get_optional can return either ERR_PTR or NULL pointer.
NULL case is not tested and then dereferenced later in desc_to_gpio.
Fix this by using non optional version which returns ERR_PTR in any
error case (this is not an optional gpio).
Use the same non optional version for the host-wake gpio.

Fixes: 765ea3ab ("Bluetooth: hci_intel: Retrieve host-wake IRQ")
Signed-off-by: Loic Poulain <loic.poulain@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>