fix: implicitly casts

Change macros to include an explicit cast to type size_t.
This was being hinted by clang-tidy of clang-14.

Signed-off-by: J-Alves <joao.alves@arm.com>
Change-Id: I4af78fcf5e5f5793584082b0b9cb61e0a9ab8f26
diff --git a/inc/hf/std.h b/inc/hf/std.h
index 4d8265a..3e37c3a 100644
--- a/inc/hf/std.h
+++ b/inc/hf/std.h
@@ -17,7 +17,7 @@
  * likely to catch errors. This may need to be relaxed if it proves to be overly
  * restrictive.
  */
-#define RSIZE_MAX (128 * 1024 * 1024)
+#define RSIZE_MAX ((size_t)(128 * 1024 * 1024))
 
 /*
  * Only the safer versions of these functions are exposed to reduce the chance