net/mlx5_core: Add error handling inmlx5_query_nic_vport_qkey_viol_cntr()

net/mlx5_core: Add error handling inmlx5_query_nic_vport_qkey_viol_cntr()

The function mlx5_query_nic_vport_qkey_viol_cntr() calls the function
mlx5_query_nic_vport_context() but does not check its return value. This
could lead to undefined behavior if the query fails. A proper
implementation can be found in mlx5_nic_vport_query_local_lb().

Add error handling for mlx5_query_nic_vport_context(). If it fails, free
the out buffer via kvfree() and return error code.

Fixes: 9efa75254593 ("net/mlx5_core: Introduce access functions to query vport RoCE fields")
Cc: stable@vger.kernel.org # v4.5
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/20250521133620.912-1-vulab@iscas.ac.cn
Signed-off-by: Paolo Abeni <pabeni@redhat.com>