ice: remove VF pointer reference in eswitch code

Make eswitch code generic by removing VF pointer reference in functions.
It is needed to support eswitch mode for other type of devices.

Previously queue id used for Rx was based on VF number. Use ::q_id saved
in port representor instead.

After adding or removing port representor ::q_id value can change. It
isn't good idea to iterate over representors list using this value.
Use xa_find starting from the first one instead to get next port
representor to remap.

The number of port representors has to be equal to ::num_rx/tx_q. Warn if
it isn't true.

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Tested-by: Sujai Buvaneswaran <sujai.buvaneswaran@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>