net/mlx5: fix Tx queue stop state

net/mlx5: fix Tx queue stop state

The Tx queue stop API doesn't call the PMD callback when the state of
the queue is stopped.
The drivers should update the state to be stopped when the queue stop
callback is done successfully or when the port is stopped.
The drivers should update the state to be started when the queue start
callback is done successfully or when the port is started.

The driver wrongly didn't update the state as started when the port
start callback was done which kept the state as stopped.
Following call to a queue stop API was not completed by ethdev layer
because the state is already stopped.

Move the state update from the Tx queue setup to the port start
callback.

Fixes: 161d103b231c ("net/mlx5: add queue start and stop")
Cc: stable@dpdk.org
Signed-off-by: Matan Azrad <matan@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>