[PATCH] USB: negative index in drivers/usb/host/isp116x-hcd.c

From: Eric Sesterhenn <snakebyte@gmx.de>

This fixes coverity Bug #390.

With the following code

	ret = ep->branch = balance(isp116x, ep->period, ep->load);
	if (ret < 0)
		goto fail;

the problem is that ret and balance are of the type int, and ep->branch is u16.
so the int balance() returns gets reduced to u16 and then converted to an int again,
which removes the sign. Maybe the following little c program can explain it better: