bcmdhd: Enable Ad-Hoc (IBSS) mode

This enables Ad-Hoc (IBSS) mode for bcmdhd. We basically just need to set the
interface flag and avoid some P2P specific settings while scanning.

Also add the "station get" command for IBSS mode.

Signed-off-by: Bruno Randolf <br1@einfach.org>

Change-Id: I10a047f76495d7fedfee16d0ac10de239e494567