Bluetooth: Add stubs for synchronous HCI request functionality

Prepare hci_request.c to have code for doing synchronous HCI requests,
such as LE scanning or advertising changes. The necessary work
callbacks will be set up in hci_request_setup() and cleaned up in
hci_request_cancel_all(). The former is used when an HCI device get
registered, and the latter each time it is powered off (or
unregistered).

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c
index ae19bce..d482062 100644
--- a/net/bluetooth/hci_request.c
+++ b/net/bluetooth/hci_request.c
@@ -845,3 +845,11 @@
 
 	return 0;
 }
+
+void hci_request_setup(struct hci_dev *hdev)
+{
+}
+
+void hci_request_cancel_all(struct hci_dev *hdev)
+{
+}