Add million seconds time type.

From RFC8446, the unit of ticket age is million seconds

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/include/mbedtls/platform_time.h b/include/mbedtls/platform_time.h
index eae6f5f..e6f7e23 100644
--- a/include/mbedtls/platform_time.h
+++ b/include/mbedtls/platform_time.h
@@ -39,6 +39,12 @@
 typedef time_t mbedtls_time_t;
 #endif /* MBEDTLS_PLATFORM_TIME_TYPE_MACRO */
 
+#if defined(MBEDTLS_PLATFORM_MS_TIME_TYPE_MACRO)
+typedef MBEDTLS_PLATFORM_MS_TIME_TYPE_MACRO mbedtls_ms_time_t;
+#else
+typedef signed long long mbedtls_ms_time_t;
+#endif /* MBEDTLS_PLATFORM_MS_TIME_TYPE_MACRO */
+
 /*
  * The function pointers for time
  */