kernel: add new ltq-vdsl-vr11 driver

kernel: add new ltq-vdsl-vr11 driver

This uses version 4.23.1 of the drv_dsl_cpe_api package from the Intel
UGW 8.5.2.10 for the VRX518.

Signed-off-by: Martin Schiller <ms.3headeddevs@gmail.com>
[rebased and updated for kernel 5.10]
Signed-off-by: Jan Hoffmann <jan@3e8.eu>
[update to 4.23.1, switch to tag tarball, update patches]
Signed-off-by: Andre Heider <a.heider@gmail.com>
[added fix for elapsed time and upstream MINEFTR]
Signed-off-by: Jan Hoffmann <jan@3e8.eu>
Signed-off-by: Andre Heider <a.heider@gmail.com>