Don't use 0-initializer for structs

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 784ab2d..7bdad3d 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -2768,7 +2768,7 @@
 static void ssl_check_id_based_session_resumption( mbedtls_ssl_context *ssl )
 {
     int ret;
-    mbedtls_ssl_session session_tmp = { 0 };
+    mbedtls_ssl_session session_tmp;
     mbedtls_ssl_session * const session = ssl->session_negotiate;
 
     /* Resume is 0  by default, see ssl_handshake_init().
@@ -2784,6 +2784,8 @@
         return;
 #endif
 
+    mbedtls_ssl_session_init( &session_tmp );
+
     ret = ssl->conf->f_get_cache( ssl->conf->p_cache,
                                   session->id,
                                   session->id_len,