usb: gadget: uvc: refactor the check for a valid buffer in the pump worker

By toggling the condition check for a valid buffer, the else path
can be completely avoided.
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20240214-uvc-gadget-cleanup-v1-2-de6d78780459@pengutronix.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/function/uvc_video.c

@@ -594,10 +594,7 @@ static void uvcg_video_pump(struct work_struct *work)
 		 */
 		spin_lock_irqsave(&queue->irqlock, flags);
 		buf = uvcg_queue_head(queue);
-
-		if (buf != NULL) {
-			video->encode(req, video, buf);
-		} else {
+		if (!buf) {
 			/*
 			 * Either the queue has been disconnected or no video buffer
 			 * available for bulk transfer. Either way, stop processing
@@ -607,6 +604,8 @@ static void uvcg_video_pump(struct work_struct *work)
 			break;
 		}
 
+		video->encode(req, video, buf);
+
 		spin_unlock_irqrestore(&queue->irqlock, flags);
 
 		spin_lock_irqsave(&video->req_lock, flags);