iwlwifi: remove unused conf variables

There are a number of conf variables that are
unused, remove them.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Wey-Yi W Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>