net/mlx5: Add error handling in mlx5_query_nic_vport_node_guid()

net/mlx5: Add error handling in mlx5_query_nic_vport_node_guid()

The function mlx5_query_nic_vport_node_guid() calls the function
mlx5_query_nic_vport_context() but does not check its return value.
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/20250524163425.1695-1-vulab@iscas.ac.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>