change time unit of ticket to milliseconds

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 eac6326..32ad7aa 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -931,28 +931,10 @@
     if (ssl_tls13_ticket_get_identity(
             ssl, &hash_alg, &identity, &identity_len) == 0) {
 #if defined(MBEDTLS_HAVE_TIME)
-        mbedtls_time_t now = mbedtls_time(NULL);
+        mbedtls_ms_time_t now = mbedtls_ms_time();
         mbedtls_ssl_session *session = ssl->session_negotiate;
         uint32_t obfuscated_ticket_age =
             (uint32_t) (now - session->ticket_received);
-
-        /*
-         * The ticket timestamp is in seconds but the ticket age is in
-         * milliseconds. If the ticket was received at the end of a second and
-         * re-used here just at the beginning of the next second, the computed
-         * age `now - session->ticket_received` is equal to 1s thus 1000 ms
-         * while the actual age could be just a few milliseconds or tens of
-         * milliseconds. If the server has more accurate ticket timestamps
-         * (typically timestamps in milliseconds), as part of the processing of
-         * the ClientHello, it may compute a ticket lifetime smaller than the
-         * one computed here and potentially reject the ticket. To avoid that,
-         * remove one second to the ticket age if possible.
-         */
-        if (obfuscated_ticket_age > 0) {
-            obfuscated_ticket_age -= 1;
-        }
-
-        obfuscated_ticket_age *= 1000;
         obfuscated_ticket_age += session->ticket_age_add;
 
         ret = ssl_tls13_write_identity(ssl, p, end,
@@ -2837,7 +2819,7 @@
 
 #if defined(MBEDTLS_HAVE_TIME)
     /* Store ticket creation time */
-    session->ticket_received = mbedtls_time(NULL);
+    session->ticket_received = mbedtls_ms_time();
 #endif
 
     ciphersuite_info = mbedtls_ssl_ciphersuite_from_id(session->ciphersuite);