qxl: Fix new function name for spice-server library

The new spice-server function to limit the number of monitors (0.12.6)
changed while development from spice_qxl_set_monitors_config_limit to
spice_qxl_max_monitors (accepted upstream).
By mistake I post patch with former name.
This patch fix the function name.
Signed-off-by: NFrediano Ziglio <fziglio@redhat.com>
Acked-by: NChristophe Fergeau <cfergeau@redhat.com>
Acked-by: NMartin Kletzander <mkletzan@redhat.com>
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>

hw/display/qxl.c

@@ -273,8 +273,7 @@ static void qxl_spice_monitors_config_async(PCIQXLDevice *qxl, int replay)
     } else {
 #if SPICE_SERVER_VERSION >= 0x000c06 /* release 0.12.6 */
         if (qxl->max_outputs) {
-            spice_qxl_set_monitors_config_limit(&qxl->ssd.qxl,
-                                                qxl->max_outputs);
+            spice_qxl_set_max_monitors(&qxl->ssd.qxl, qxl->max_outputs);
         }
 #endif
         qxl->guest_monitors_config = qxl->ram->monitors_config;