iwlwifi: remove IWL_DEVICE_22560/IWL_DEVICE_FAMILY_22560

This is dead code, nothing uses the IWL_DEVICE_22560 macro and
thus nothing every uses IWL_DEVICE_FAMILY_22560. Remove it all.

While at it, remove some code and definitions used only in this
case, and clean up some comments/names that still refer to it.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>