net/mlx5: E-Switch, Handle representors creation in handler context

Unified representors creation in esw_functions_changed context
handler. Emulate the esw_function_changed event for FW/HW that
does not support this event.

Signed-off-by: Vu Pham <vuhuong@mellanox.com>
Reviewed-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Bodong Wang <bodong@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>