HAL in_get_parameters: do not return unknown keys

out_get_parameters and adv_get_parameters only return keys that are
supported. That allows the client the discriminate between keys not
supported and empty return value.

in_get_parameters used to have this behaviour too until it was broken by
I4f4142aba495e9625b17ba007280f76fbc66a641.

This patch restores the original in_get_parameters behaviour.

Test: vts-tradefed run vts --module VtsHalAudioV2_0Target
Bug: b/63801053
Change-Id: I8888f61f0b908aaa436577729a2c9d8b35955b6d
Signed-off-by: Kevin Rocard <krocard@google.com>
diff --git a/hal/audio_hw.c b/hal/audio_hw.c
index d7769ff..21dc9ed 100644
--- a/hal/audio_hw.c
+++ b/hal/audio_hw.c
@@ -3140,7 +3140,7 @@
     if (replied) {
         str = str_parms_to_str(reply);
     } else {
-        str = strdup(keys);
+        str = strdup("");
     }
     str_parms_destroy(query);
     str_parms_destroy(reply);