wl12xx: implement fw status debugfs entries

Implement the operations that are necessary to fetch the
wl12xx-specific FW statistics.  Re-add some of the code removed from
wlcore.

Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>
5 files changed