staging: wlan-ng: cfg80211.c: Fix sparse warnings

Include necessary header files to avoid "should be static" sparse warning
Signed-off-by: Tair Rzayev <tair.rzayev@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wlan-ng/cfg80211.c

 /* cfg80211 Interface for prism2_usb module */
+#include "hfa384x.h"
+#include "prism2mgmt.h"
 
 
 /* Prism2 channel/frequency/bitrate declarations */