chore: fix `clang-tidy` warnings

Fix warnings introduced by previous commit.

Change-Id: I3884f8a774860905ddf3d4554f986fde16ec9919
Signed-off-by: Karl Meakin <karl.meakin@arm.com>
diff --git a/inc/hf/offset_size_header.h b/inc/hf/offset_size_header.h
index 6fcf558..7182dd8 100644
--- a/inc/hf/offset_size_header.h
+++ b/inc/hf/offset_size_header.h
@@ -54,14 +54,14 @@
 #define DEFINE_SIZEOF(sym, type)                                 \
 	void gen_header__##sym(void)                             \
 	{                                                        \
-		static_assert(sizeof(type) == sym,               \
+		static_assert(sizeof(type) == (sym),             \
 			      "Generated struct size mismatch"); \
 	}
 
 #define DEFINE_OFFSETOF(sym, type, field)                          \
 	void gen_header__##sym(void)                               \
 	{                                                          \
-		static_assert(offsetof(type, field) == sym,        \
+		static_assert(offsetof(type, field) == (sym),      \
 			      "Generated struct offset mismatch"); \
 	}