update: keep zeroize helper available

Make wolfBoot_zeroize unconditional in update_flash.c so the common final-swap scrub compiles in non-encrypted builds.

F/CI

Author: danielinux

src/update_flash.c

@@ -33,8 +33,18 @@
 
 #include "delta.h"
 #include "printf.h"
+static void wolfBoot_zeroize(void *ptr, size_t len)
+{
+    volatile uint8_t *p = (volatile uint8_t *)ptr;
+
+    while (len-- > 0) {
+        *p++ = 0;
+    }
+}
+
 #ifdef EXT_ENCRYPTED
 int wolfBoot_force_fallback_iv(int enable);
+#include "encrypt.h"
 #endif
 #ifdef WOLFBOOT_TPM
 #include "tpm.h"
@@ -43,19 +53,6 @@ int wolfBoot_force_fallback_iv(int enable);
 int WP11_Library_Init(void);
 #endif
 
-#ifdef EXT_ENCRYPTED
-#include "encrypt.h"
-
-static void wolfBoot_zeroize(void *ptr, size_t len)
-{
-    volatile uint8_t *p = (volatile uint8_t *)ptr;
-
-    while (len-- > 0) {
-        *p++ = 0;
-    }
-}
-#endif /* EXT_ENCRYPTED */
-
 #ifdef MMU
 #error "MMU is not yet supported for update_flash.c, please consider update_ram.c instead"
 #endif