brcmfmac: fix error handling of irq_of_parse_and_map

Return value of irq_of_parse_and_map() is unsigned int, with 0
indicating failure, so testing for negative result never works.

Signed-off-by: Dmitry Torokhov <dtor@chromium.org>
Cc: stable@vger.kernel.org # v3.17
Acked-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -40,8 +40,8 @@ void brcmf_of_probe(struct brcmf_sdio_dev *sdiodev)
 		return;
 
 	irq = irq_of_parse_and_map(np, 0);
-	if (irq < 0) {
-		brcmf_err("interrupt could not be mapped: err=%d\n", irq);
+	if (!irq) {
+		brcmf_err("interrupt could not be mapped\n");
 		devm_kfree(dev, sdiodev->pdata);
 		return;
 	}