iwlwifi: remove unused macros

Found with W=2, remove unused macros in C files. In one case
move the macro under the corresponding ifdef.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20220204122220.068c6052689b.Idbb7a87c2fd93619c1765c7f4ed15190c3fef2a7@changeid


Signed-off-by: Luca Coelho <luciano.coelho@intel.com>