virtio_net: Use new RSS config structs

The new RSS configuration structures allow easily constructing data for
VIRTIO_NET_CTRL_MQ_RSS_CONFIG as they strictly follow the order of data
for the command.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Link: https://patch.msgid.link/20250321-virtio-v2-3-33afb8f4640b@daynix.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>