net/mlx5: E-switch, Tide up eswitch config sequence

Currently for PF and ECPF vports, representors are created before
their eswitch hardware ports are initialized in below flow.

mlx5_eswitch_enable()
  esw_offloads_init()
    esw_offloads_load_all_reps()
[..]
esw_enable_vport()

However for VFs, vports are initialized before creating their
respective netdev represnetors in event handling context.

Similarly while disabling eswitch, first hardware vports are disabled,
followed by destroying their representors.
Here while underlying vports gets destroyed but its respective user
facing netdevice can still exist on which user can continue to perform
more offload operations.

Instead, its more accurate to do
enable_eswitch switchdev mode:
1. perform FDB tables initialization
2. initialize hw vport
3. create and publish representor for this vport

disable_eswitch switchdev mode:
1. destroy user facing representor for the vport
2. disable hw vport
3. perform FDB tables cleanup

Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>