net/mlx5: Move state lock taking into mlx5_sf_dealloc()

Instead of taking lock and calling mlx5_sf_dealloc(), move the lock
taking into mlx5_sf_dealloc(). The other caller of mlx5_sf_dealloc()
does not need it now, but will need it after a follow-up patch removing
the table reference counting.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Shay Drory <shayd@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>