staging: brcm80211: Fix double include introduced by bad merge

A merge with Linus' tree added a double include of linux/interrupt.h.
Fix by removing one of the includes.

Signed-off-by: Daniel Morsing <daniel.morsing@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/staging/brcm80211/brcmsmac/mac80211_if.h

@@ -24,8 +24,6 @@
 #define BRCMS_SET_SHORTSLOT_OVERRIDE		146
 
 
-#include <linux/interrupt.h>
-
 /* BMAC Note: High-only driver is no longer working in softirq context as it needs to block and
  * sleep so perimeter lock has to be a semaphore instead of spinlock. This requires timers to be
  * submitted to workqueue instead of being on kernel timer