Use error corruption detection as initial return value

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/library/ssl_msg.c b/library/ssl_msg.c
index 33751c7..826c532 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -5123,7 +5123,7 @@
  */
 static int ssl_handle_hs_message_post_handshake( mbedtls_ssl_context *ssl )
 {
-    int ret;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
     /*
      * - For client-side, expect SERVER_HELLO_REQUEST.