cmake: remove deprecated `set_conf_file()` support

The `set_conf_file()` was deprecated in
6d4ba3490fee518da9136ce54d45d82200e800c6

which is before Zephyr v1.14 LTS.
Let's remove the support now, before releasing a new LTS.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>
1 file changed