staging: keucr: remove needless check before usb_free_coherent()

usb_free_coherent() is safe with NULL addr and this check is
not required.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/keucr/usb.c

@@ -442,10 +442,7 @@ static void dissociate_dev(struct us_data *us)
 	kfree(us->sensebuf);
 
 	/* Free the device-related DMA-mapped buffers */
-	if (us->cr)
-		usb_free_coherent(us->pusb_dev, sizeof(*us->cr), us->cr,
-								us->cr_dma);
-	if (us->iobuf)
+	usb_free_coherent(us->pusb_dev, sizeof(*us->cr), us->cr, us->cr_dma);
 	usb_free_coherent(us->pusb_dev, US_IOBUF_SIZE, us->iobuf,
 			  us->iobuf_dma);