[MDC-111] simetbox-openwrt-base: select simetbox-openwrt-simet-ma

[MDC-111] simetbox-openwrt-base: select simetbox-openwrt-simet-ma

Since we now need simet-ma to do geolocation, it is no longer possible
to "live without it" and have a full-legacy simetbox.  Enforce this
using a SELECT in simetbox-openwrt-base, otherwise we'd have a circular
dependency