usb: gadget: udc: core: don't starve DMA resources

BugLink: https://bugs.launchpad.net/bugs/1878232

commit 23fd537c upstream.

Always unmap all SG entries as required by DMA API

Fixes: a698908d ("usb: gadget: add generic map/unmap request utilities")
Cc: <stable@vger.kernel.org> # v3.4+
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ian May <ian.may@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

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

@@ -97,7 +97,7 @@ void usb_gadget_unmap_request(struct usb_gadget *gadget,
 		return;
 
 	if (req->num_mapped_sgs) {
-		dma_unmap_sg(gadget->dev.parent, req->sg, req->num_mapped_sgs,
+		dma_unmap_sg(gadget->dev.parent, req->sg, req->num_sgs,
 				is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
 
 		req->num_mapped_sgs = 0;