usb: dwc3: gadget: fix high speed multiplier setting

For High-Speed Transfers the prepare_one_trb function is calculating the
multiplier setting for the trb based on the length parameter of the trb
currently prepared. This assumption is wrong. For trbs with a sg list,
the length of the actual request has to be taken instead.

Fixes: 40d829fb ("usb: dwc3: gadget: Correct ISOC DATA PIDs for short packets")
Cc: stable <stable@kernel.org>
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20220704141812.1532306-3-m.grzeschik@pengutronix.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/gadget.c

@@ -1265,10 +1265,10 @@ static void dwc3_prepare_one_trb(struct dwc3_ep *dep,
 				unsigned int mult = 2;
 				unsigned int maxp = usb_endpoint_maxp(ep->desc);
 
-				if (trb_length <= (2 * maxp))
+				if (req->request.length <= (2 * maxp))
 					mult--;
 
-				if (trb_length <= maxp)
+				if (req->request.length <= maxp)
 					mult--;
 
 				trb->size |= DWC3_TRB_SIZE_PCM1(mult);