display: remove compiler warnings

Use correct typecasts and format specifiers and resolve
compiler warnings

Change-Id: I51b12ecb78a9a496cf1f76c3d32892a203f70c43
diff --git a/libgralloc/ionalloc.cpp b/libgralloc/ionalloc.cpp
index 2097320..ccf6ed5 100644
--- a/libgralloc/ionalloc.cpp
+++ b/libgralloc/ionalloc.cpp
@@ -114,7 +114,7 @@
     data.base = base;
     data.fd = fd_data.fd;
     ioctl(mIonFd, ION_IOC_FREE, &handle_data);
-    ALOGD_IF(DEBUG, "ion: Allocated buffer base:%p size:%u fd:%d",
+    ALOGD_IF(DEBUG, "ion: Allocated buffer base:%p size:%zu fd:%d",
           data.base, ionAllocData.len, data.fd);
     return 0;
 }