hal: Add support to use compress path for ec ref loopback

Add support to use compress path for mic and ec reference data
capture in single stream.
Modify parsing logic of custom mtmx param tags to reflect changes
in platform xml.

Change-Id: Iebbd56de6ab95f35c695205cdd14bf928321eead
diff --git a/hal/msm8960/platform.c b/hal/msm8960/platform.c
index 137e700..e3d1b7b 100644
--- a/hal/msm8960/platform.c
+++ b/hal/msm8960/platform.c
@@ -357,7 +357,8 @@
     platform_get_custom_mtmx_params
     (
         void *platform __unused,
-        struct audio_custom_mtmx_params_info *info __unused
+        struct audio_custom_mtmx_params_info *info __unused,
+        uint32_t *idx __unused
     )
 {
     ALOGW("%s: not implemented!", __func__);