Staging: brcm80211: typedefs.h: remove NULL definition

No need for a driver to define NULL, the core kernel handles that.

Cc: Brett Rudley <brudley@broadcom.com>
Cc: Henry Ptasinski <henryp@broadcom.com>
Cc: Nohee Ko <noheek@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/brcm80211/include/typedefs.h

@@ -96,10 +96,6 @@ typedef signed int int32;
 #define TRUE	1		/* TRUE */
 #endif
 
-#ifndef NULL
-#define	NULL	0
-#endif
-
 #ifndef OFF
 #define	OFF	0
 #endif