Fix problem with dropouts with multiple USB audio streams.

Bug 17136569

Change-Id: I94bdbe037533a3fd77f249fdd42f4d828d3bf87f
diff --git a/modules/usbaudio/alsa_device_profile.c b/modules/usbaudio/alsa_device_profile.c
index f214eab..8c34b84 100644
--- a/modules/usbaudio/alsa_device_profile.c
+++ b/modules/usbaudio/alsa_device_profile.c
@@ -92,6 +92,14 @@
     return profile->is_valid;
 }
 
+bool profile_is_cached_for(alsa_device_profile* profile, int card, int device) {
+    return card == profile->card && device == profile->device;
+}
+
+void profile_decache(alsa_device_profile* profile) {
+    profile->card = profile->device = -1;
+}
+
 /*
  * Returns the supplied value rounded up to the next even multiple of 16
  */