[U-Boot] [PATCH v3 28/31] virtio: net: Support non-legacy device

[sjg at google.com]

For v1.0 compliant device, it always assumes the member 'num_buffers'
exists in the struct virtio_net_hdr while the legacy driver only
presented 'num_buffers' when VIRTIO_NET_F_MRG_RXBUF was negotiated.
Without that feature the structure was 2 bytes shorter.

Update the driver to support the non-legacy device.

Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
Reviewed-by: Simon Glass <sjg at chromium.org>
---

Changes in v3: None
Changes in v2: None

 drivers/virtio/virtio_net.c | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

Applied to u-boot-dm/next, thanks!