virtio_net: Allocate rss_hdr with devres

virtnet_probe() lacks the code to free rss_hdr in its error path.
Allocate rss_hdr with devres so that it will be automatically freed.

Fixes: 86a48a00 ("virtio_net: Support dynamic rss indirection table size")
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-v2-4-33afb8f4640b@daynix.com


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