net-sysfs: get_netdev_queue_index() cleanup

Redo commit ed1acc8c.

Commit 822b3b2e ("net: Add max rate tx queue
attribute") moved get_netdev_queue_index around, but kept the old version.
Probably because of a reuse of the original patch from before Eric's change to
that function.

Remove one inline keyword, and no need for a loop to find
an index into a table.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@redhat.com>
Fixes: 822b3b2e ("net: Add max rate tx queue attribute")
Acked-by: Or Gerlitz <ogerlitz@mellanox.com>
Acked-by: John Fastabend <john.r.fastabend@intel.com>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>