uvc-gadget: Don't hardcode the maximum payload transfer size

Use the streaming endpoint maximum packet size parsed from ConfigFS
instead of hardcoding an arbitrary value.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

uvc-gadget.c

diff --git a/uvc-gadget.c b/uvc-gadget.c
index 5ec81fb..8ccfa07 100644
--- a/uvc-gadget.c
+++ b/uvc-gadget.c
@@ -298,7 +298,7 @@
 		break;
 	}
 
-	ctrl->dwMaxPayloadTransferSize = 512;	/* TODO this should be filled by the driver. */
+	ctrl->dwMaxPayloadTransferSize = dev->fc->streaming.ep.wMaxPacketSize;
 	ctrl->bmFramingInfo = 3;
 	ctrl->bPreferedVersion = 1;
 	ctrl->bMaxVersion = 1;