brcmfmac: fix uninitialized warning in brcmf_usb_probe_phase2()

This fixes the following warning:

  drivers/net/wireless/broadcom/brcm80211/brcmfmac/usb.c: In function
  'brcmf_usb_probe_phase2':
  drivers/net/wireless/broadcom/brcm80211/brcmfmac/usb.c:1198:2:
  warning: 'devinfo' may be used uninitialized in this function
  [-Wmaybe-uninitialized]
    mutex_unlock(&devinfo->dev_init_lock);

Fixes: 6d0507a7 ("brcmfmac: add parameter to pass error code in firmware callback")
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

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

@@ -1164,14 +1164,13 @@ static void brcmf_usb_probe_phase2(struct device *dev, int ret,
 				   void *nvram, u32 nvlen)
 {
 	struct brcmf_bus *bus = dev_get_drvdata(dev);
-	struct brcmf_usbdev_info *devinfo;
+	struct brcmf_usbdev_info *devinfo = bus->bus_priv.usb->devinfo;
 
 	if (ret)
 		goto error;
 
 	brcmf_dbg(USB, "Start fw downloading\n");
 
-	devinfo = bus->bus_priv.usb->devinfo;
 	ret = check_file(fw->data);
 	if (ret < 0) {
 		brcmf_err("invalid firmware\n");