wifi: mac80211: simplify non-chanctx drivers

There are still surprisingly many non-chanctx drivers, but in
mac80211 that code is a bit awkward. Simplify this by having
those drivers assign 'emulated' ops, so that the mac80211 code
can be more unified between non-chanctx/chanctx drivers. This
cuts the number of places caring about it by about 15, which
are scattered across - now they're fewer and no longer in the
channel context handling.

Link: https://msgid.link/20240129194108.6d0ead50f5cf.I60d093b2fc81ca1853925a4d0ac3a2337d5baa5b@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>