turris_1x: Normalize Kconfig usage

We don't set many options in the board Kconfig entry file but instead
use defconfigs, select in some cases on the target itself, or update the
"default" options of the main entries when needed. In this case we can
remove most of the board Kconfig entries and just add them to the
defconfig like other platforms.

Signed-off-by: Tom Rini <trini@konsulko.com>