hwc: resolve compiler warnings

- remove unused variables.
- fix incorrect castings.

Change-Id: I7661edb4539a3ffc7d4aedbb9f633bc5ba1dc149
diff --git a/libhwcomposer/hwc_copybit.h b/libhwcomposer/hwc_copybit.h
index 4d8123c..f7be644 100644
--- a/libhwcomposer/hwc_copybit.h
+++ b/libhwcomposer/hwc_copybit.h
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2010 The Android Open Source Project
- * Copyright (C) 2012-2013, The Linux Foundation. All rights reserved.
+ * Copyright (C) 2012-2014, The Linux Foundation. All rights reserved.
  *
  * Not a Contribution, Apache license notifications and license are retained
  * for attribution purposes only.
@@ -54,7 +54,7 @@
     struct copybit_device_t *mEngine;
     // Helper functions for copybit composition
     int  drawLayerUsingCopybit(hwc_context_t *dev, hwc_layer_1_t *layer,
-                          private_handle_t *renderBuffer, int dpy, bool isFG);
+                          private_handle_t *renderBuffer, bool isFG);
     int fillColorUsingCopybit(hwc_layer_1_t *layer,
                           private_handle_t *renderBuffer);
     bool canUseCopybitForYUV (hwc_context_t *ctx);