virtio_net: Split struct virtio_net_rss_config

struct virtio_net_rss_config was less useful in actual code because of a
flexible array placed in the middle. Add new structures that split it
into two to avoid having a flexible array in the middle.

Suggested-by: Jason Wang <jasowang@redhat.com>
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-v2-1-33afb8f4640b@daynix.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: akihikodaki

include/uapi/linux/virtio_net.h

@@ -327,6 +327,19 @@ struct virtio_net_rss_config {
 	__u8 hash_key_data[/* hash_key_length */];
 };
 
+struct virtio_net_rss_config_hdr {
+	__le32 hash_types;
+	__le16 indirection_table_mask;
+	__le16 unclassified_queue;
+	__le16 indirection_table[/* 1 + indirection_table_mask */];
+};
+
+struct virtio_net_rss_config_trailer {
+	__le16 max_tx_vq;
+	__u8 hash_key_length;
+	__u8 hash_key_data[/* hash_key_length */];
+};
+
  #define VIRTIO_NET_CTRL_MQ_RSS_CONFIG          1
 
 /*