iwlwifi: mvm: check family instead of new TX API for workarounds

There are two workarounds because RSS is currently broken on A000
devices due to firmware issues, but checking for the new TX API
doesn't really make sense. Check the hardware family instead of
the new TX API - there's nothing better to check since it's just
a temporary workaround.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>