net/mlx5: SF, Fix show state inactive when its inactivated

When a SF is inactivated and when it is in a TEARDOWN_REQUEST
state, driver still returns its state as active. This is incorrect.
Fix it by treating TEARDOWN_REQEUST as inactive state. When a SF
is still attached to the driver, on user request to reactivate EINVAL
error is returned. Inform user about it with better code EBUSY and
informative error message.

Fixes: 6a327321 ("net/mlx5: SF, Port function state change support")
Signed-off-by: Parav Pandit <parav@nvidia.com>
Reviewed-by: Vu Pham <vuhuong@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>