Bluetooth: Remove unnecessary NULL check before vfree()

Remove unnecessary NULL check which causes coccinelle warning:

net/bluetooth/coredump.c:104:2-7: WARNING: NULL check before some
freeing functions is not needed.
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

net/bluetooth/coredump.c

@@ -100,8 +100,7 @@ void hci_devcd_reset(struct hci_dev *hdev)
 /* Call with hci_dev_lock only. */
 static void hci_devcd_free(struct hci_dev *hdev)
 {
-	if (hdev->dump.head)
-		vfree(hdev->dump.head);
+	vfree(hdev->dump.head);
 
 	hci_devcd_reset(hdev);
 }