brcmfmac: fix build regression

This fixes a build regression for x86_64 target that showed up
in 3.7-rc1 due to:

commit 1a873342
Author: Hante Meuleman <meuleman@broadcom.com>
Date:   Thu Sep 27 14:17:54 2012 +0200

    brcmfmac: add hostap supoort.
Reported-by: Yuanhan Liu <yuanhan.liu@intel.com>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/brcm80211/brcmfmac/wl_cfg80211.c

@@ -3515,7 +3515,7 @@ brcmf_cfg80211_start_ap(struct wiphy *wiphy, struct net_device *ndev,
 	WL_TRACE("channel_type=%d, beacon_interval=%d, dtim_period=%d,\n",
 		 settings->channel_type, settings->beacon_interval,
 		 settings->dtim_period);
-	WL_TRACE("ssid=%s(%d), auth_type=%d, inactivity_timeout=%d\n",
+	WL_TRACE("ssid=%s(%zu), auth_type=%d, inactivity_timeout=%d\n",
 		 settings->ssid, settings->ssid_len, settings->auth_type,
 		 settings->inactivity_timeout);