wifi: iwlwifi: cleanup BT Shared Single Antenna code

We don't support such device.

Reviewed-by: Gregory Greenman <gregory.greenman@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20231219215605.6e6961ac0ac5.I923024eac20efd24a5b42332d8e73ae756e0469a@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>