configs: support 4 ch EC-ref for FFV

- FFV now supports 4 ch EC ref, enable it for Red Dragon.

Change-Id: I464d54247b30a95f64d14e236c67b70570bbf3d2
diff --git a/configs/sdm710/sound_trigger_platform_info.xml b/configs/sdm710/sound_trigger_platform_info.xml
index 9604b93..08dbebd 100644
--- a/configs/sdm710/sound_trigger_platform_info.xml
+++ b/configs/sdm710/sound_trigger_platform_info.xml
@@ -65,7 +65,7 @@
         <!-- ec reference loopback params -->
         <!-- split_ec_ref_data - true if ec ref is packed with mic captured data -->
         <param split_ec_ref_data="false"/>
-        <param ec_ref_channel_count="2"/>
+        <param ec_ref_channel_count="4"/>
 
         <!-- Profile specific data which the algorithm can support -->
         <param sample_rate="16000" />