ublox: use send-delay=0 by default

Looks like the u-blox SARA-U260 requires this, see:
https://lists.freedesktop.org/archives/modemmanager-devel/2017-May/004670.html

plugins/ublox/mm-broadband-modem-ublox.c

@@ -898,6 +898,32 @@ modem_create_bearer (MMIfaceModem        *self,
     create_bearer_step (task);
 }
 
+/*****************************************************************************/
+/* Setup ports (Broadband modem class) */
+
+static void
+setup_ports (MMBroadbandModem *self)
+{
+    MMPortSerialAt *ports[2];
+    guint           i;
+
+    /* Call parent's setup ports first always */
+    MM_BROADBAND_MODEM_CLASS (mm_broadband_modem_ublox_parent_class)->setup_ports (self);
+
+    ports[0] = mm_base_modem_peek_port_primary   (MM_BASE_MODEM (self));
+    ports[1] = mm_base_modem_peek_port_secondary (MM_BASE_MODEM (self));
+
+    /* Configure AT ports */
+    for (i = 0; i < G_N_ELEMENTS (ports); i++) {
+        if (!ports[i])
+            continue;
+
+        g_object_set (ports[i],
+                      MM_PORT_SERIAL_SEND_DELAY, (guint64) 0,
+                      NULL);
+    }
+}
+
 /*****************************************************************************/
 
 MMBroadbandModemUblox *
@@ -963,6 +989,9 @@ static void
 mm_broadband_modem_ublox_class_init (MMBroadbandModemUbloxClass *klass)
 {
     GObjectClass          *object_class = G_OBJECT_CLASS (klass);
+    MMBroadbandModemClass *broadband_modem_class = MM_BROADBAND_MODEM_CLASS (klass);
 
     g_type_class_add_private (object_class, sizeof (MMBroadbandModemUbloxPrivate));
+
+    broadband_modem_class->setup_ports = setup_ports;
 }

plugins/ublox/mm-plugin-ublox.c

@@ -75,6 +75,7 @@ mm_plugin_create (void)
                                     MM_PLUGIN_ALLOWED_VENDOR_STRINGS, vendor_strings,
                                     MM_PLUGIN_ALLOWED_AT,             TRUE,
                                     MM_PLUGIN_CUSTOM_AT_PROBE,        custom_at_probe,
+                                    MM_PLUGIN_SEND_DELAY,             0,
                                     NULL));
 }