wl18xx: add runtime configuration parameters

Now wlcore requires the lower drivers to set the correct
configuration.  Move the existing private configuration to the proper
place and add all generic configuration parameters.

The important changes are in Tx interrupt pacing and Rx BA window size.

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