HAL out_get_parameters: do not return unknown keys
am: edf0b4c690

Change-Id: I78ad525fe4a03fba07485f4b99726194147e9b58
diff --git a/hal/audio_hw.c b/hal/audio_hw.c
index 30c0637..6ca763e 100644
--- a/hal/audio_hw.c
+++ b/hal/audio_hw.c
@@ -2094,7 +2094,7 @@
         str_parms_add_str(reply, AUDIO_PARAMETER_STREAM_SUP_CHANNELS, value);
         str = str_parms_to_str(reply);
     } else {
-        str = strdup(keys);
+        str = strdup("");
     }
     str_parms_destroy(query);
     str_parms_destroy(reply);