brcmfmac: check for wowl support before enumerating feature flag

In some cases wiphy->wowlan could be NULL if firmware doesn't have the
support. Driver should check for support before walking down the feature
flags.
Reviewed-by: Arend Van Spriel <arend@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c

@@ -6594,7 +6594,8 @@ struct brcmf_cfg80211_info *brcmf_cfg80211_attach(struct brcmf_pub *drvr,
 	if (brcmf_feat_is_enabled(ifp, BRCMF_FEAT_SCAN_RANDOM_MAC)) {
 		wiphy->features |= NL80211_FEATURE_SCHED_SCAN_RANDOM_MAC_ADDR;
 #ifdef CONFIG_PM
-		if (wiphy->wowlan->flags & WIPHY_WOWLAN_NET_DETECT)
+		if (wiphy->wowlan &&
+		    wiphy->wowlan->flags & WIPHY_WOWLAN_NET_DETECT)
 			wiphy->features |= NL80211_FEATURE_ND_RANDOM_MAC_ADDR;
 #endif
 	}