FIH: Fix possible static check error caused by FIH_DECLARE

Signed-off-by: Sherry Zhang <sherry.zhang2@arm.com>
Change-Id: I970582777018094d0cbf83d3131a7d5c576035e5
diff --git a/boot/bootutil/include/bootutil/fault_injection_hardening.h b/boot/bootutil/include/bootutil/fault_injection_hardening.h
index 518c137..65a400a 100644
--- a/boot/bootutil/include/bootutil/fault_injection_hardening.h
+++ b/boot/bootutil/include/bootutil/fault_injection_hardening.h
@@ -249,8 +249,7 @@
 #endif /* FIH_ENABLE_DOUBLE_VARS */
 
 #define FIH_DECLARE(var, val) \
-    fih_ret var; \
-    FIH_SET(var, val);
+    fih_ret FIH_SET(var, val)
 
 /* C has a common return pattern where 0 is a correct value and all others are
  * errors. This function converts 0 to FIH_SUCCESS and any other number to a