hwc: Fix klockwork errors

Resolving klockwork errors to avoid memory leaks,
improper assignments in liboverlay.

Change-Id: I82ac6ae782c7b783e89999b832bbd1d361376b9f
diff --git a/libgralloc/gralloc.cpp b/libgralloc/gralloc.cpp
index 6b41ce6..c1c61aa 100644
--- a/libgralloc/gralloc.cpp
+++ b/libgralloc/gralloc.cpp
@@ -105,6 +105,9 @@
         gpu_context_t *dev;
         IAllocController* alloc_ctrl = IAllocController::getInstance();
         dev = new gpu_context_t(m, alloc_ctrl);
+        if(!dev)
+            return status;
+
         *device = &dev->common;
         status = 0;
     } else {