vmm: Add multiple queue option and update config for virtio-net device

Add num_queues and queue_size for virtio-net device to make them configurable,
while add the associated options in command line.

Update cloud-hypervisor.yaml with the new options for NetConfig.

Signed-off-by: Cathy Zhang <cathy.zhang@intel.com>

src/main.rs

@@ -131,7 +131,8 @@ fn create_app<'a, 'b>(
                 .help(
                     "Network parameters \"tap=<if_name>,\
                      ip=<ip_addr>,mask=<net_mask>,mac=<mac_addr>,\
-                     iommu=on|off\"",
+                     iommu=on|off,num_queues=<number_of_queues>,\
+                     queue_size=<size_of_each_queue>\"",
                 )
                 .takes_value(true)
                 .min_values(1)