Rename functions and add test messages

Change-Id: Iab51b031ae82d7b2d384de708858be64be75f9ed
Signed-off-by: XiaokangQian <xiaokang.qian@arm.com>
diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index 5c693bd..b23b0c5 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -692,7 +692,7 @@
 
 #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
 
-int mbedtls_ssl_tls13_write_pre_shared_key_ext_without_binders(
+int mbedtls_ssl_tls13_write_identities_of_pre_shared_key_ext(
     mbedtls_ssl_context *ssl,
     unsigned char *buf, unsigned char *end,
     size_t *out_len, size_t *binders_len )