4.4.0-83.106) is not available, but a newer one is (4.4.0-142.168). We redirected you there.
/lib/firmware/updates/3.2.0-126-generic/ is in linux-backports-modules-cw-3.7-3.2.0-126-generic 3.2.0-126.118.
This file is owned by root:root, with mode 0o755.