lantiq: use wpad-mini for WBMR boards

The WBMR boards are the only ones in the whole tree selecting the wpad
and hostapd-utils package by default.

Remove the wps uci-default script as well, there is no obvious reason
why the wps config need to be set only for this board.

Signed-off-by: Mathias Kresin <dev@kresin.me>