wifi: iwlwifi: fix byte count table for old devices

For devices handled by iwldvm, bc_table_dword was never set, but I missed
that during the removal thereof. Change the logic to not treat the byte
count table as dwords for devices older than 9000 series to fix that.

Fixes: 6570ea22 ("wifi: iwlwifi: remove bc_table_dword transport config")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20250828095500.eccd7d3939f1.Ibaffa06d0b3aa5f35a9451d94af34de208b8a2bc@changeid