display: Reconcile display HALs

Make the display HALs compile with/without the Qualcomm BSP
specific features so they can work with pure AOSP.
Change-Id: I1ad7282c4fe1fe7e3309afb530a07735f165ffbe
diff --git a/libhwcomposer/hwc_mdpcomp.cpp b/libhwcomposer/hwc_mdpcomp.cpp
index 760b134..5314943 100644
--- a/libhwcomposer/hwc_mdpcomp.cpp
+++ b/libhwcomposer/hwc_mdpcomp.cpp
@@ -379,7 +379,7 @@
     overlay::Overlay& ov = *ctx->mOverlay;
     int availablePipes = ov.availablePipes(dpy);
 
-    if(numAppLayers < 1 || numAppLayers > (uint32_t)availablePipes) {
+    if(numAppLayers < 1 || numAppLayers > availablePipes) {
         ALOGD_IF(isDebug(), "%s: Unsupported number of layers",__FUNCTION__);
         return false;
     }