wifi: iwlwifi: mvm: fix A-MSDU checks

Since Gl A-step devices use the old checksum hardware,
we shouldn't use the Bz code to check for A-MSDU
combining ability; fix that.

Fixes: ec18e7d4 ("wifi: iwlwifi: mvm: use old checksum for Bz A-step")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230413102635.8c445b943fee.Ibf772102ca712f59e2ee0cdd4c344011fcf445aa@changeid


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