hwc: resolve compiler warnings

- remove unused variables.
- fix incorrect castings.

Change-Id: I7661edb4539a3ffc7d4aedbb9f633bc5ba1dc149
diff --git a/libhwcomposer/hwc_ad.cpp b/libhwcomposer/hwc_ad.cpp
index 929ccc4..7f9ce9d 100644
--- a/libhwcomposer/hwc_ad.cpp
+++ b/libhwcomposer/hwc_ad.cpp
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2013 The Linux Foundation. All rights reserved.
+* Copyright (c) 2013-2014 The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
@@ -270,12 +270,12 @@
     return true;
 }
 
-int AssertiveDisplay::getDstFd(hwc_context_t *ctx) const {
+int AssertiveDisplay::getDstFd() const {
     overlay::Writeback *wb = overlay::Writeback::getInstance();
     return wb->getDstFd();
 }
 
-uint32_t AssertiveDisplay::getDstOffset(hwc_context_t *ctx) const {
+uint32_t AssertiveDisplay::getDstOffset() const {
     overlay::Writeback *wb = overlay::Writeback::getInstance();
     return wb->getOffset();
 }