Revert commit 33af72df in order to not depend on test code

Signed-off-by: Michael Schuster <michael@schuster.ms>

programs/cipher/cipher_aead_demo.c

@@ -35,8 +35,6 @@
 
 #include "mbedtls/cipher.h"
 
-#include <test/helpers.h>
-
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
@@ -80,6 +78,16 @@ const unsigned char msg2_part2[] = { 0x15, 0x16, 0x17 };
  * 32-byte is enough to all the key size supported by this program. */
 const unsigned char key_bytes[32] = { 0x2a };
 
+/* Print the contents of a buffer in hex */
+void print_buf(const char *title, unsigned char *buf, size_t len)
+{
+    printf("%s:", title);
+    for (size_t i = 0; i < len; i++) {
+        printf(" %02x", buf[i]);
+    }
+    printf("\n");
+}
+
 /* Run an Mbed TLS function and bail out if it fails.
  * A string description of the error code can be recovered with:
  * programs/util/strerror <value> */
@@ -190,7 +198,7 @@ static int aead_encrypt(mbedtls_cipher_context_t *ctx, size_t tag_len,
     p += tag_len;
 
     olen = p - out;
-    mbedtls_test_print_buf("out", out, olen);
+    print_buf("out", out, olen);
 
 exit:
     return ret;