audioflinger: enable volume listener on direct outputs

Always allow effects with no process function on any output
thread type as there is no impact on performance and no risk of
the audio properties not being supported by the effect.

Bug: 63015903
Test: place a Skype call over SCO and verify the volume listener
can be created.

Change-Id: I99db7802cec88a618808e500b74f4c78165199fe
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index a67acd6..1bd840e 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -1169,6 +1169,11 @@
         return BAD_VALUE;
     }
 
+    // always allow effects without processing load or latency
+    if ((desc->flags & EFFECT_FLAG_NO_PROCESS_MASK) == EFFECT_FLAG_NO_PROCESS) {
+        return NO_ERROR;
+    }
+
     switch (mType) {
     case MIXER: {
         // Reject any effect on mixer multichannel sinks.
@@ -1199,10 +1204,6 @@
                 }
             }
 
-            // always allow effects without processing load or latency
-            if ((desc->flags & EFFECT_FLAG_NO_PROCESS_MASK) == EFFECT_FLAG_NO_PROCESS) {
-                break;
-            }
             if (flags & AUDIO_OUTPUT_FLAG_RAW) {
                 ALOGW("checkEffectCompatibility_l(): effect %s on playback thread in raw mode",
                       desc->name);