wifi: iwlwifi: don't load old firmware for Bz

This is a future product, don't try to load ancient
firmware images for it, they don't exist anyway.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230621130443.a6961592f258.Ib7afecd46b1963164481c2acf35d2582691ef0bc@changeid


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