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/vmapi/hf/ffa.h b/inc/vmapi/hf/ffa.h
index 0bf05ae..4db2c14 100644
--- a/inc/vmapi/hf/ffa.h
+++ b/inc/vmapi/hf/ffa.h
@@ -144,7 +144,7 @@
  * be confused with PAGE_SIZE, which is the translation granule Hafnium is
  * configured to use.
  */
-#define FFA_PAGE_SIZE 4096
+#define FFA_PAGE_SIZE ((size_t)4096)
 
 /** The ID of a VM. These are assigned sequentially starting with an offset. */
 typedef uint16_t ffa_vm_id_t;