iwlwifi: mvm: change the firmware name loading

The firmware moved the development from a0 MAC to z0.
z0 is using the same RFID and device ID as a0 so we only
need to switch the name.

Signed-off-by: Mordechai Goodstein <mordechay.goodstein@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>