usb:udc:s3c: Reduce dcache invalidate range for UDC receive buffer

The s3c udc driver sends data in a max packet size. Therefore the dcache
invalidate range shall be equal to max packet, not the entire
DMA_BUFFER_SIZE.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Cc: Marek Vasut <marex@denx.de>

drivers/usb/gadget/s3c_udc_otg_xfer_dma.c

@@ -117,7 +117,8 @@ static int setdma_rx(struct s3c_ep *ep, struct s3c_request *req)
 
 	invalidate_dcache_range((unsigned long) ep->dev->dma_buf[ep_num],
 				(unsigned long) ep->dev->dma_buf[ep_num]
-				+ DMA_BUFFER_SIZE);
+				+ ROUND(ep->ep.maxpacket,
+					CONFIG_SYS_CACHELINE_SIZE));
 
 	if (length == 0)
 		pktcnt = 1;