virtio_net: enable napi for all possible queues during open

virtio_net: enable napi for all possible queues during open

Commit a4bd6e63bb102428cd9a2b5655a7fe6eacfa6f05 (virtio-net: fill only rx
queues which are being used) only does the napi enabling during open for
curr_queue_pairs. This will break multiqueue receiving since napi of new queues
were still disabled after changing the number of queues.

This patch fixes this by enabling napi for all possible queues during open.

Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>