iwlwifi: bump FW API to 71 for AX devices

Start supporting API version 71 for AX devices.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20220304131517.d0898482506f.I2de2f9140c23f39a837f68199bbaf15a20f26abb@changeid


Signed-off-by: Luca Coelho <luciano.coelho@intel.com>