brcmfmac: include linux/atomic.h

brcmfmac uses atomic_or() and other atomic_* functions, but does not
include linux/atomic.h. This file gets included by some other header
file so this normally does not cause problems.
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Acked-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/brcm80211/brcmfmac/sdio.c

@@ -15,6 +15,7 @@
  */
 
 #include <linux/types.h>
+#include <linux/atomic.h>
 #include <linux/kernel.h>
 #include <linux/kthread.h>
 #include <linux/printk.h>