libgralloc: use proper types and type casts

- Use proper types for pointers
- Resolve compiler errors
- handle proper type casts
- remove unused variables

Change-Id: I628ebe174485d30abadea4ca40b67f9aab1a0652
diff --git a/libgralloc/fb_priv.h b/libgralloc/fb_priv.h
index 01af2e1..0ff082f 100644
--- a/libgralloc/fb_priv.h
+++ b/libgralloc/fb_priv.h
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2008 The Android Open Source Project
- * Copyright (c) 2012, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2012-2014, The Linux Foundation. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,7 +41,7 @@
     uint32_t fbFormat;
     uint32_t flags;
     uint32_t numBuffers;
-    uint32_t bufferMask;
+    size_t   bufferMask;
     pthread_mutex_t lock;
     private_handle_t *currentBuffer;
     struct fb_var_screeninfo info;
@@ -51,7 +51,6 @@
     float ydpi;
     float fps;
     uint32_t swapInterval;
-    uint32_t currentOffset;
 };