Revert flags assignment in test-app

Author: danielinux

test-app/Makefile

@@ -679,7 +679,7 @@ ifeq ($(TARGET),aurix_tc3xx)
 endif
 
 # Capture final flags for locally built wolfSSL objects.
-WOLFSSL_CFLAGS=$(CFLAGS)
+WOLFSSL_CFLAGS:=$(CFLAGS)
 
 ifeq ($(WOLFHSM_CLIENT),1)
   CFLAGS += -DSTRING_USER -I"$(WOLFBOOT_LIB_WOLFSSL)"