usb: gadget: r8a66597-udc: fix flush fifo handling

The "BCLR" in CFIFOCTR/DnFIFOCTR can flush the fifo of "CPU side" only.
To flush the fifo of "SIE side", we have to use the "ACLRM" in PIPEnCTR.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/r8a66597-udc.c

@@ -1718,6 +1718,8 @@ static void r8a66597_fifo_flush(struct usb_ep *_ep)
 	if (list_empty(&ep->queue) && !ep->busy) {
 		pipe_stop(ep->r8a66597, ep->pipenum);
 		r8a66597_bclr(ep->r8a66597, BCLR, ep->fifoctr);
+		r8a66597_write(ep->r8a66597, ACLRM, ep->pipectr);
+		r8a66597_write(ep->r8a66597, 0, ep->pipectr);
 	}
 	spin_unlock_irqrestore(&ep->r8a66597->lock, flags);
 }