p54: fix beaconing related firmware crash

This patch fixes a firmware crash which can be provoked by changing
operation mode.

Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Christian Lamparter <chunkeey@web.de>
Tested-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/p54/p54.h b/drivers/net/wireless/p54/p54.h
index 584b156..1afc394 100644
--- a/drivers/net/wireless/p54/p54.h
+++ b/drivers/net/wireless/p54/p54.h
@@ -211,6 +211,7 @@
 	u16 aid;
 	bool powersave_override;
 	__le32 beacon_req_id;
+	struct completion beacon_comp;
 
 	/* cryptographic engine information */
 	u8 privacy_caps;