brcmfmac: Accept only first creditmap event.

During P2P testing it turned out that the firmware sents multiple
multiple creditmap event messages. Only the first message from the
firmware should be processed. Otherwise the firmware-signalled flow
control can run haywire when it has packets outstanding in firmware.
Reviewed-by: NArend Van Spriel <arend@broadcom.com>
Signed-off-by: NHante Meuleman <meuleman@broadcom.com>
Signed-off-by: NArend van Spriel <arend@broadcom.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

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

@@ -434,6 +434,7 @@ struct brcmf_fws_info {
 	u32 fifo_delay_map;
 	unsigned long borrow_defer_timestamp;
 	bool bus_flow_blocked;
+	bool creditmap_received;
 };
 
 /*
@@ -1356,6 +1357,10 @@ static int brcmf_fws_notify_credit_map(struct brcmf_if *ifp,
 		brcmf_err("event payload too small (%d)\n", e->datalen);
 		return -EINVAL;
 	}
+	if (fws->creditmap_received)
+		return 0;
+
+	fws->creditmap_received = true;
 
 	brcmf_dbg(TRACE, "enter: credits %pM\n", credits);
 	brcmf_fws_lock(ifp->drvr, flags);