Add Routing property to MediaTransport interface

This should indicate to the endpoint what routing the transport is using
diff --git a/audio/transport.c b/audio/transport.c
index d575590..b5a9e48 100644
--- a/audio/transport.c
+++ b/audio/transport.c
@@ -599,12 +599,16 @@
 						DBusMessageIter *dict)
 {
 	gboolean nrec, inband;
+	const char *routing;
 
 	nrec = headset_get_nrec(transport->device);
 	dict_append_entry(dict, "NREC", DBUS_TYPE_BOOLEAN, &nrec);
 
 	inband = headset_get_inband(transport->device);
 	dict_append_entry(dict, "InbandRingtone", DBUS_TYPE_BOOLEAN, &inband);
+
+	routing = headset_get_sco_hci(transport->device) ? "HCI" : "PCM";
+	dict_append_entry(dict, "Routing", DBUS_TYPE_STRING, &routing);
 }
 
 void transport_get_properties(struct media_transport *transport,
diff --git a/doc/media-api.txt b/doc/media-api.txt
index 92b8b3f..84903d6 100644
--- a/doc/media-api.txt
+++ b/doc/media-api.txt
@@ -152,3 +152,9 @@
 			Optional. Indicates if the transport support sending
 			ringtones, this property is only writeable when the
 			transport was acquired by the sender.
+
+		string Routing [readonly]
+
+			Optional. Indicates where is the transport being routed
+
+			Possible Values: "HCI" or "PCM"