drivers: bluetooth: hci_nxp: fix unexpected command complete event

As the previous version of the MCXW71 BLE Controller wasn't sending a
command complete event after setting the BD address, we used a
workaround to directly send the HCI command without using zephyr's API.
Now, on the latest version of MCXW72 and MCXW71, this issue is fixed,
so we need to use `bt_hci_cmd_send_sync` to properly expect the
command complete event.

Signed-off-by: Axel Le Bourhis <axel.lebourhis@nxp.com>