wlcore/wl18xx: change priority calculations for links

Update the 18xx FW status private part to include Tx related link
priorities. Introduce new HW ops to determine link priority per chip
family.

For 18xx the changes are:
- Suspended links are at most low priority and Tx for them is stopped
  beyond the suspend threshold.
- Active links now get their thresholds directly from FW
- There's a new "stop" threshold for active links, at which point a link
  stops receiving new packets.

Update the min 18xx FW version required to make sure suspended links
bitmap is advertised by the FW.

Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>