[MDC-433] simetbox-openwrt-simet-{ma,lmapd}: fix removal race

[MDC-433] simetbox-openwrt-simet-{ma,lmapd}: fix removal race

Package simetbox-openwrt-simet-lmapd might get removed before
simetbox-openwrt-simet-ma during an opkg run.

We must stop simet-lmapd in that case, and handle the fact that
the binaries will be gone before the initscript is (because the
initscript is in ...simet-ma, not ...simet-lmapd).