brcmfmac: fix system warning message during wowl suspend

There is a system warning message, warn_slowpath-fmt, during suspend
while using supplicant join AP and enable wowl feature by IW command.
It's caused by brcmf_pno_remove_request path can't find the reqid.
This fix will not go to remove pno request function if there is no
pno scan.
Acked-by: NArend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: NLo-Hsiang Lo <double.lo@cypress.com>
Signed-off-by: NChi-Hsien Lin <chi-hsien.lin@cypress.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>

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

@@ -496,6 +496,11 @@ int brcmf_pno_stop_sched_scan(struct brcmf_if *ifp, u64 reqid)
 	brcmf_dbg(TRACE, "reqid=%llu\n", reqid);
 
 	pi = ifp_to_pno(ifp);
+
+	/* No PNO request */
+	if (!pi->n_reqs)
+		return 0;
+
 	err = brcmf_pno_remove_request(pi, reqid);
 	if (err)
 		return err;