Virtio PCI: added support for MSI-X interrupts

* make use of MSI/MSI-X PCI x86 API
* MSI support untested because QEmu only offers MSI-X
* changed a bit the Virtio bus API by adding a queue count parameter
for the setup_interrupt() hook.

headers/private/virtio/virtio.h

@@ -84,7 +84,7 @@ typedef struct {
 	
 	uint16	(*get_queue_ring_size)(void* cookie, uint16 queue);
 	status_t (*setup_queue)(void* cookie, uint16 queue, phys_addr_t phy);
-	status_t (*setup_interrupt)(void* cookie);
+	status_t (*setup_interrupt)(void* cookie, uint16 queueCount);
 	void	(*notify_queue)(void* cookie, uint16 queue);
 } virtio_sim_interface;