ipq806x: update 4.19 kernel config

These changes are needed in order to migrate old kernel 4.14 config to
the upcoming kernel version 4.19.  Also add missing configuration
options that comes up with this SoC.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
[line wrap long commit description, add 4.19 to subject, soc->SoC]
Signed-off-by: Petr Štetiar <ynezz@true.cz>