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>

drivers/net/wireless/ti/wl18xx/Kconfig

 config WL18XX
-       tristate "TI wl18xx support"
-       select WLCORE
-       ---help---
+	tristate "TI wl18xx support"
+	depends on MAC80211
+	select WLCORE
+	---help---
 	  This module adds support for wireless adapters based on TI
 	  WiLink 8 chipsets.