display: Fix warnings

Treat warnings as errors again

Change-Id: Ibd7f484d31ad420b85e82fd5183d70bf7dce4bfa
diff --git a/libhwcomposer/hwc_ad.cpp b/libhwcomposer/hwc_ad.cpp
index f849450..679e6d6 100644
--- a/libhwcomposer/hwc_ad.cpp
+++ b/libhwcomposer/hwc_ad.cpp
@@ -135,7 +135,7 @@
         const hwc_layer_1_t* layer = &list->hwLayers[nYuvIndex];
         private_handle_t *hnd = (private_handle_t *)layer->handle;
         qdutils::MDPVersion& mdpHw =  qdutils::MDPVersion::getInstance();
-        if(hnd && hnd->width <= mdpHw.getMaxMixerWidth()) {
+        if(hnd && hnd->width <= (int) mdpHw.getMaxMixerWidth()) {
             mDoable = true;
         }
     }