Put MPS under the umbrella of the TLS 1.3 experimental configuration

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/library/mps_trace.c b/library/mps_trace.c
index 28b05bb..dc0577d 100644
--- a/library/mps_trace.c
+++ b/library/mps_trace.c
@@ -19,6 +19,10 @@
  *  This file is part of Mbed TLS (https://tls.mbed.org)
  */
 
+#include "common.h"
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+
 #include "mps_common.h"
 
 #if defined(MBEDTLS_MPS_ENABLE_TRACE)
@@ -120,3 +124,4 @@
 }
 
 #endif /* MBEDTLS_MPS_ENABLE_TRACE */
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */