brcmfmac: fix memory leak in brcmf_fill_bss_param

commit 23e9c128 upstream.

This function is called from get_station callback which means that every
time user space was getting/dumping station(s) we were leaking 2 KiB.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Fixes: 1f0dc59a ("brcmfmac: rework .get_station() callback")
Acked-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

@@ -2408,7 +2408,7 @@ static void brcmf_fill_bss_param(struct brcmf_if *ifp, struct station_info *si)
 				     WL_BSS_INFO_MAX);
 	if (err) {
 		brcmf_err("Failed to get bss info (%d)\n", err);
-		return;
+		goto out_kfree;
 	}
 	si->filled |= BIT(NL80211_STA_INFO_BSS_PARAM);
 	si->bss_param.beacon_interval = le16_to_cpu(buf->bss_le.beacon_period);
@@ -2420,6 +2420,9 @@ static void brcmf_fill_bss_param(struct brcmf_if *ifp, struct station_info *si)
 		si->bss_param.flags |= BSS_PARAM_FLAGS_SHORT_PREAMBLE;
 	if (capability & WLAN_CAPABILITY_SHORT_SLOT_TIME)
 		si->bss_param.flags |= BSS_PARAM_FLAGS_SHORT_SLOT_TIME;
+
+out_kfree:
+	kfree(buf);
 }
 
 static s32