Pixelflinger: Fix issue of pointers being stored in ints

Pixelflinger's code makes assumptions, at certain places,
that pointers can be stored as ints. This patch makes use
of uintptr_t wherever pointers are stored as int or cast
to int.

Change-Id: Ie76f425cbc82ac038a747f77a95bd31774f4a8e8
Signed-off-by: Ashok Bhat <ashok.bhat@arm.com>
diff --git a/libpixelflinger/buffer.cpp b/libpixelflinger/buffer.cpp
index af7356b..cbdab5a 100644
--- a/libpixelflinger/buffer.cpp
+++ b/libpixelflinger/buffer.cpp
@@ -93,7 +93,7 @@
         gen.width   = s.width;
         gen.height  = s.height;
         gen.stride  = s.stride;
-        gen.data    = int32_t(s.data);
+        gen.data    = uintptr_t(s.data);
     }
 }