Bluetooth: Update discovery state earlier in hci_discovery_set_state

In a subsequent patch the hci_update_background_scan() function will
depend on being able to know the current discovery state. For this to be
possible we need to set the new state early in the function. Since we
also need to check what the old state was this patch introduces an extra
variable for tracking it.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

net/bluetooth/hci_core.c

@@ -1903,16 +1903,20 @@ bool hci_discovery_active(struct hci_dev *hdev)
 
 void hci_discovery_set_state(struct hci_dev *hdev, int state)
 {
+	int old_state = hdev->discovery.state;
+
 	BT_DBG("%s state %u -> %u", hdev->name, hdev->discovery.state, state);
 
-	if (hdev->discovery.state == state)
+	if (old_state == state)
 		return;
 
+	hdev->discovery.state = state;
+
 	switch (state) {
 	case DISCOVERY_STOPPED:
 		hci_update_background_scan(hdev);
 
-		if (hdev->discovery.state != DISCOVERY_STARTING)
+		if (old_state != DISCOVERY_STARTING)
 			mgmt_discovering(hdev, 0);
 		break;
 	case DISCOVERY_STARTING:
@@ -1925,8 +1929,6 @@ void hci_discovery_set_state(struct hci_dev *hdev, int state)
 	case DISCOVERY_STOPPING:
 		break;
 	}
-
-	hdev->discovery.state = state;
 }
 
 void hci_inquiry_cache_flush(struct hci_dev *hdev)