In mue_iff() move the initialization of the hash table up so that is done

In mue_iff() move the initialization of the hash table up so that is done
unconditionally, like it's done on other devices, so that we don't end up in
the situation of the card being put in promiscuous mode or if
ac->ac_multirangecnt > 0 and then we would write into the table while being
uninitialized a little bit later.

Noticed on Coverity ID 1473316.

hint from claudio@ and kettenis@
OK kevlo@ claudio@