Bluetooth: Add definitions for link key types

Introduce the link key types defs and use them instead of magic numbers.

Signed-off-by: Waldemar Rymarkiewicz <waldemar.rymarkiewicz@tieto.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 98aa24b..07d0ba3 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -1050,7 +1050,7 @@
 	if (new_key)
 		mgmt_new_key(hdev->id, key, old_key_type);
 
-	if (type == 0x06)
+	if (type == HCI_LK_CHANGED_COMBINATION)
 		key->type = old_key_type;
 
 	return 0;