net/mlx5: E-switch, Introduce helper function to enable/disable vports

vports needs to be enabled in switchdev and legacy mode.

In switchdev mode, vports should be enabled after initializing
the FDB tables and before creating their represntors so that
representor works on an initialized vport object.

Prepare a helper function which can be called when enabling either of
the eswitch modes.

Similarly, have disable vports helper function.

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