bcmdhd: Enable Ad-Hoc (IBSS) mode

Enable 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.

Change-Id: Ice320bc65b0b9b738fa09acc1e3dea2a58805ad9
Signed-off-by: Bruno Randolf <br1@einfach.org>