wl18xx: add dependency on mac80211

Add a dependency on mac80211 in Kconfig, and also replace some spaces
with tabs.

Reported-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>