xhci: Fix an error in count_sg_trbs_needed()

The expression

	while (running_total < sg_dma_len(sg))

does not take into account that the remaining data length can be less
than sg_dma_len(sg). In that case, running_total can end up being
greater than the total data length, so an extra TRB is counted.
Changing the expression to

	while (running_total < sg_dma_len(sg) && running_total < temp)

fixes that.

This patch should be queued for stable kernels back to 2.6.31.
Signed-off-by: NPaul Zimmerman <paulz@synopsys.com>
Signed-off-by: NSarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@kernel.org

drivers/usb/host/xhci-ring.c

@@ -2374,7 +2374,7 @@ static unsigned int count_sg_trbs_needed(struct xhci_hcd *xhci, struct urb *urb)
 			num_trbs++;
 
 		/* How many more 64KB chunks to transfer, how many more TRBs? */
-		while (running_total < sg_dma_len(sg)) {
+		while (running_total < sg_dma_len(sg) && running_total < temp) {
 			num_trbs++;
 			running_total += TRB_MAX_BUFF_SIZE;
 		}