engine: Set SinglePCI to false when importing VNC display

When importing VM the OVF reader (which read from the export domain)
need  additional check to remove the default SinglePCI for VNC display.

Bug-Url: https://bugzilla.redhat.com/1075294
Change-Id: I39c4d1dd45f3fa91b5fe3f0a7e786a26eb66fb29
Signed-off-by: Shahar Havivi <shaharh@redhat.com>