watchdog: pcwd_usb: remove needless check before usb_free_coherent()

usb_free_coherent() is safe with NULL usb_pcwd->intr_buffer and
this check is not required.

Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200713055348.21620-1-vulab@iscas.ac.cn
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

Author: ISCAS-Vulab

drivers/watchdog/pcwd_usb.c

@@ -585,9 +585,8 @@ static struct notifier_block usb_pcwd_notifier = {
 static inline void usb_pcwd_delete(struct usb_pcwd_private *usb_pcwd)
 {
 	usb_free_urb(usb_pcwd->intr_urb);
-	if (usb_pcwd->intr_buffer != NULL)
-		usb_free_coherent(usb_pcwd->udev, usb_pcwd->intr_size,
-				  usb_pcwd->intr_buffer, usb_pcwd->intr_dma);
+	usb_free_coherent(usb_pcwd->udev, usb_pcwd->intr_size,
+			  usb_pcwd->intr_buffer, usb_pcwd->intr_dma);
 	kfree(usb_pcwd);
 }