virtio_pci: drop useless del_vqs call

Device VQs were getting freed twice: once in every device's removal
functions, and then again in virtio_pci_legacy_remove().  The ones in
devices are called first, so drop the useless second call.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>