lantiq-vdsl-fw: update to provide recent vectoring firmware

lantiq-vdsl-fw: update to provide recent vectoring firmware

Recent Speedport firmware downloads only work over HTTPS, so the user
either needs to provide the already downloaded file or install
ustream-ssl-* as well as ca-certificates or ca-bundle.

So to get VDSL2 with vectoring on xRX200, simply run
vdsl_fw_install.sh
on the target and either provide the downloaded file as instructed or
make sure the device is connected to the Internet and can download that
HTTPS url itself.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>