iwlwifi: mvm: parse firmware alive message version 6

iwlwifi: mvm: parse firmware alive message version 6

There's a new version with some addition, we'll need to
do something with the additional data later, but for now
just parse it so we don't fail with the newer firmware.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20211204083238.f856cb190a4e.I77e3ff5a92b1bcc3e81c1344b046dade0a8b6a24@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>