usb-uhci: fix expire time initialization.

expire_time must be initialited when the guest activates the
usb scheduler, not at device creation time.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

hw/usb-uhci.c

@@ -424,6 +424,8 @@ static void uhci_ioport_writew(void *opaque, uint32_t addr, uint32_t val)
     case 0x00:
         if ((val & UHCI_CMD_RS) && !(s->cmd & UHCI_CMD_RS)) {
             /* start frame processing */
+            s->expire_time = qemu_get_clock_ns(vm_clock) +
+                (get_ticks_per_sec() / FRAME_TIMER_FREQ);
             qemu_mod_timer(s->frame_timer, qemu_get_clock_ns(vm_clock));
             s->status &= ~UHCI_STS_HCHALTED;
         } else if (!(val & UHCI_CMD_RS)) {
@@ -1131,8 +1133,6 @@ static int usb_uhci_common_initfn(UHCIState *s)
         usb_port_location(&s->ports[i].port, NULL, i+1);
     }
     s->frame_timer = qemu_new_timer_ns(vm_clock, uhci_frame_timer, s);
-    s->expire_time = qemu_get_clock_ns(vm_clock) +
-        (get_ticks_per_sec() / FRAME_TIMER_FREQ);
     s->num_ports_vmstate = NB_PORTS;
     QTAILQ_INIT(&s->async_pending);