iwlwifi: bump FW API to 59 for AX devices

Start supporting API version 59 for AX devices.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/iwlwifi.20201008181047.0359498107fe.I559b5140be6abbee5eb759ec6e5ca046f7178f8f@changeid