lantiq: fix console print

The boot loader of many boards provides a kernel boot argument with a
broken console parameter to the kernel. This will be taken before the
stdout-path defined in device tree and the serial will not work on this
board. Multiple boards are affected by this problem, so revert this
patch for all boards. Later we can remove the boot arguments from the
device tree again, after the individual board was checked to work.

This partly reverts this commit:
commit 4995c648
Author: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Date:   Sun Dec 11 21:55:00 2016 +0100

    lantiq: specify console using stdout-path instead of cmdline argument

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>