EHCI : Fix a regression in the ISO scheduler

Fix a regression that was introduced by commit
811c926c538f7e8d3c08b630dd5844efd7e000f6 (USB: EHCI: fix HUB TT scheduling
issue with iso transfer).

We detect an error if next == start, but this means uframe 0 can't be allocated
anymore for iso transfer...

Reported-by: Sander Eikelenboom <[e-mail]>
Signed-off-by: Matthieu CASTET <[e-mail]>
Acked-by: Alan Stern <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/host/ehci-sched.c

···
 	 * jump until after the queue is primed.
 	 */
 	else {
+		int done = 0;
 		start = SCHEDULE_SLOP + (now & ~0x07);
 
 		/* NOTE:  assumes URB_ISO_ASAP, to limit complexity/bugs */
···
 			if (stream->highspeed) {
 				if (itd_slot_ok(ehci, mod, start,
 						stream->usecs, period))
-					break;
+					done = 1;
 			} else {
 				if ((start % 8) >= 6)
 					continue;
 				if (sitd_slot_ok(ehci, mod, stream,
 						start, sched, period))
-					break;
+					done = 1;
 			}
-		} while (start > next);
+		} while (start > next && !done);
 
 		/* no room in the schedule */
-		if (start == next) {
+		if (!done) {
 			ehci_dbg(ehci, "iso resched full %p (now %d max %d)\n",
 				urb, now, now + mod);
 			status = -ENOSPC;