Revert "doc: Kconfig: Decode Kconfig sources as UTF-8 instead [...]"

This reverts commit f8d451258e51797c68f3b6d07f5c53066ddb3be3. The
revert is done because of a regression in Mac OSX
https://github.com/zephyrproject-rtos/zephyr/issues/6726

Signed-off-by: Sebastian Bøe <sebastian.boe@nordicsemi.no>
2 files changed