staging: slicoss: return early before calling request_firmware with empty firmware filename

when the device id doesn't match in slic_card_download_gbrcv the filename is "",
i.e an empty name, and we try calling request_firmware with that name,
actually we can just fail out at default case before even calling request_firmware
Signed-off-by: Devendra Naga <devendra.aaru@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/slicoss/slicoss.c

@@ -514,8 +514,7 @@ static int slic_card_download_gbrcv(struct adapter *adapter)
 		file = "slicoss/gbrcvucode.sys";
 		break;
 	default:
-		ASSERT(0);
-		break;
+		return -ENOENT;
 	}
 
 	ret = request_firmware(&fw, file, &adapter->pcidev->dev);