esp: Remove user_creatable flag

esp devices aren't going to work with -device, as they need IRQs
to be connected and mmio to be mapped (this is done by
esp_init()). Remove the user_creatable flag from the device
class.

Cc: Marcel Apfelbaum <marcel@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: NMarcel Apfelbaum <marcel@redhat.com>
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Message-Id: <20170503203604.31462-16-ehabkost@redhat.com>
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>

hw/scsi/esp.c

@@ -728,11 +728,6 @@ static void sysbus_esp_class_init(ObjectClass *klass, void *data)
     dc->reset = sysbus_esp_hard_reset;
     dc->vmsd = &vmstate_sysbus_esp_scsi;
     set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
-    /*
-     * FIXME: Set only because we are not sure yet if this device
-     * will be outside the q35 sysbus whitelist.
-     */
-    dc->user_creatable = true;
 }
 
 static const TypeInfo sysbus_esp_info = {