usb: gadget: udc: Remove useless variable assignment in xudc_read_fifo()

This patch removes the unused variables assignment warning.
Value assigned to variable bufferspace is overwritten, before
it can be used. This makes such variable assignment useless.

Reported Coverity warning: UNUSED_VALUE

Signed-off-by: Piyush Mehta <piyush.mehta@xilinx.com>
Link: https://lore.kernel.org/r/20220506175349.10102-1-piyush.mehta@xilinx.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/udc-xilinx.c

@@ -632,7 +632,7 @@ top:
 		dev_dbg(udc->dev, "read %s, %d bytes%s req %p %d/%d\n",
 			ep->ep_usb.name, count, is_short ? "/S" : "", req,
 			req->usb_req.actual, req->usb_req.length);
-		bufferspace -= count;
+
 		/* Completion */
 		if ((req->usb_req.actual == req->usb_req.length) || is_short) {
 			if (udc->dma_enabled && req->usb_req.length)