net/mlx5: Release tunnel device after tc update skb

The cited commit causes a regression. Tunnel device is not released
after tc update skb if skb needs to be freed. The following error
message will be printed:

  unregister_netdevice: waiting for vxlan1 to become free. Usage count = 11

Fix it by releasing tunnel device if skb needs to be freed.

Fixes: 93a1ab2c ("net/mlx5: Refactor tc miss handling to a single function")
Signed-off-by: Chris Mi <cmi@nvidia.com>
Reviewed-by: Maor Dickman <maord@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>