virtio_net: Add TX stopped and wake counters

Add a tx queue stop and wake counters, they are useful for debugging.

$ ./tools/net/ynl/cli.py --spec netlink/specs/netdev.yaml \
--dump qstats-get --json '{"scope": "queue"}'
...
 {'ifindex': 13,
  'queue-id': 0,
  'queue-type': 'tx',
  'tx-bytes': 14756682850,
  'tx-packets': 226465,
  'tx-stop': 113208,
  'tx-wake': 113208},
 {'ifindex': 13,
  'queue-id': 1,
  'queue-type': 'tx',
  'tx-bytes': 18167675008,
  'tx-packets': 278660,
  'tx-stop': 8632,
  'tx-wake': 8632}]

Signed-off-by: Daniel Jurgens <danielj@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Link: https://lore.kernel.org/r/20240510201927.1821109-3-danielj@nvidia.com


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