net/mlx5e: E-Switch, Initialize eswitch only if eswitch manager

Execute mlx5_eswitch_init() only if we have MLX5_ESWITCH_MANAGER
capabilities.
Do the same for mlx5_eswitch_cleanup().

Fixes: a9f7705f ("net/mlx5: Unify vport manager capability check")
Signed-off-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>