hal: Correct compilation errors in hal

Correct compilation errors due to merge of new changes

Change-Id: I83cea7c5d672d24b81bbb767eafc3e1564be561a
diff --git a/hal/audio_extn/passthru.c b/hal/audio_extn/passthru.c
index 1ee0008..f8974c7 100644
--- a/hal/audio_extn/passthru.c
+++ b/hal/audio_extn/passthru.c
@@ -535,7 +535,7 @@
           platform_get_snd_device_name(out_snd_device));
 
     /* Check if the channels are supported */
-    if (max_edid_channels < backend_cfg.channels) {
+    if (max_edid_channels < (int)backend_cfg.channels) {
 
         ALOGE("%s: ERROR: Unsupported channels in passthru mode!!!"
               " max_edid_channels - %d backend_channels - %d",