Actually use the READ_TIMEOUT_MS in the sample DTLS client and server

Signed-off-by: Ryan LaPointe <ryan@ryanlapointe.org>
diff --git a/programs/ssl/dtls_client.c b/programs/ssl/dtls_client.c
index 03a06ff..8c302a0 100644
--- a/programs/ssl/dtls_client.c
+++ b/programs/ssl/dtls_client.c
@@ -191,6 +191,7 @@
     mbedtls_ssl_conf_ca_chain( &conf, &cacert, NULL );
     mbedtls_ssl_conf_rng( &conf, mbedtls_ctr_drbg_random, &ctr_drbg );
     mbedtls_ssl_conf_dbg( &conf, my_debug, stdout );
+    mbedtls_ssl_conf_read_timeout( &conf, READ_TIMEOUT_MS );
 
     if( ( ret = mbedtls_ssl_setup( &ssl, &conf ) ) != 0 )
     {