LinuxKPI wlan drivers: update makefiles to not use WITH_

[bz]

Summary

Up to now the LinuxKPI wlan drivers were using local variables starting
with a WITH_ prefix. That is likely to collide with other mechanisms
like WITH_ and WITHOUT_ from src.conf. Adjust the local variables to
use a driver name prefix for now to control what is built and what is
not. These variables are mainly for the time of development so we can
turn off/on a feature or bus attachment while working on it. Otherwise
they are there for documentation purposes. The only reason one would
change them locally would be if someone was to build a very custom
image and not want certain bits (e.g., USB support) being compiled into
the modules.

While here, try to harmonize some parts of the Makefiles.

Suggested by: imp
Discussed with: imp
Sponsored by: The FreeBSD Foundation
MFC after: 3 days

[bz]

@imp this is mostly just to glance at if you think the names like this would be fine.

There is a lot more churn in it given I tried to have them all have the same order, comments, ... and I felt like re-doing it and splitting it up into two or more changes would be .. unnecessary unless someone thought differently.

You don't have to Accept the review; I'll be happy with just a comment of "looks okay" or similar...

[bz]

@imp if you could have a glance, better now? Otherwise I'll commit this the next days.

[imp]

@bz: this is exactly what I was hoping for. thank you so much for reworking it like this.