wifi: rework MAINTAINERS entries a bit

wifi: rework MAINTAINERS entries a bit

Since I really don't want to be CC'ed on every patch
add X: entries for all the drivers that are otherwise
covered. In some cases, add a bit more to drivers that
have other entries, mostly for the vendor directories,
but for libertas also add libertas_tf.

While at it, also add all nl80211-related (vendor)
UAPI header files to the nl80211 entry.

Link: https://patch.msgid.link/20250306092831.f7fdfe7df7b2.I7c86da443038af32e9bcbaa5f53b1e4128a0d1f9@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>