parser xml BUGFIX action needs operation node as well

Fixes cesnet/libnetconf2#354
diff --git a/src/parser_xml.c b/src/parser_xml.c
index 97d2253..145fe0e 100644
--- a/src/parser_xml.c
+++ b/src/parser_xml.c
@@ -1457,7 +1457,7 @@
         rc = LY_EVALID;
         goto cleanup;
     }
-    if ((int_opts & (LYD_INTOPT_RPC | LYD_INTOPT_NOTIF | LYD_INTOPT_REPLY)) && !lydctx->op_node) {
+    if ((int_opts & (LYD_INTOPT_RPC | LYD_INTOPT_ACTION | LYD_INTOPT_NOTIF | LYD_INTOPT_REPLY)) && !lydctx->op_node) {
         LOGVAL(ctx, LYVE_DATA, "Missing the operation node.");
         rc = LY_EVALID;
         goto cleanup;