base-files: rework _ucidef_set_interface to be more generic

base-files: rework _ucidef_set_interface to be more generic

This is a rework of previously submitted patch reworking
ucidef_set_interface_raw [1]. Here, keep the idea but instead
make _ucidef_set_interface more generic and use it instead of
ucidef_set_interface_raw.
Also change the users like ucidef_set_interface_lan and others.

[1] https://patchwork.ozlabs.org/patch/844961/

Signed-off-by: Roman Yeryomin <[email protected]>