android/client: Change interface name to bluetooth

This changes 'adapter' to 'bluetooth' as name of HAL interface.
This name matches name fond in bluetooth.h where all interfaces
are defined.

android/client/if-bt.c

@@ -777,6 +777,6 @@ static struct method methods[] = {
 };
 
 const struct interface bluetooth_if = {
-	.name = "adapter",
+	.name = "bluetooth",
 	.methods = methods
 };