wifi: iwlwifi: cfg: clean up BW limit and subdev matching

The BW limit, cores and RF ID are matched in the subdevice ID,
so it doesn't really make sense to have both SUBDEV() match and
a match on any of those three. In particular, for Killer devices
the subdevice ID doesn't even follow the layout, so no matching
should be on those three values at all, only with SUBDEV().

Change the logic around the BW limit to have it more like all
the other things: only a bw_limit match in the dev_info, and
put the actual bandwidth into struct iwl_cfg. This duplicates a
number of those values, but that way the logic is clearer.

Add a test that checks that the three matches mentioned above
are not used in conjunction with SUBDEV(), and check that if
the bw_limit is matched, a BW limit is provided in the config.
Also check that the "Killer" devices have a SUBDEV() match.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20250502155404.a185eac2736c.I87ee87300c92518a1d3296d3eda9fd4163e9085e@changeid