vdpa/mlx5: fix virtq cleaning

vdpa/mlx5: fix virtq cleaning

The HW virtq object can be destroyed either when the device is closed or
when the state of the virtq becomes disabled.

Some parameters of the virtq should continue to be managed when the
virtq state is changed but all of them must be initialized when the
device is closed.

Wrongly, the enable parameter stayed on when the device is closed what
might cause creation of invalid virtq in the next time a device is
assigned to the driver.

Clean all the virtqs memory when the device is closed.

Fixes: c47d6e83334e ("vdpa/mlx5: support queue update")
Cc: stable@dpdk.org
Signed-off-by: Matan Azrad <matan@nvidia.com>
Acked-by: Xueming Li <xuemingl@nvidia.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>