fix lenght mismatch error

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index 736cd20..41d2a32 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -184,6 +184,8 @@
                            ( "client hello, got %" MBEDTLS_PRINTF_SIZET " ciphersuites",
                              buf_len/2 ) );
 
+    *olen = ciphersuite_iter - buf;
+
     return( 0 );
 }