usb-host: claim port

When configured to pass through a specific host port (using hostbus and
hostport properties), try to claim the port if supported by the kernel.
That will avoid any kernel drivers binding to devices plugged into that
port.  It will not stop any userspace apps (such as usb_modeswitch)
access the device via usbfs though.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff --git a/trace-events b/trace-events
index e473aef..a6e0cb4 100644
--- a/trace-events
+++ b/trace-events
@@ -263,6 +263,7 @@
 usb_host_reset(int bus, int addr) "dev %d:%d"
 usb_host_auto_scan_enabled(void)
 usb_host_auto_scan_disabled(void)
+usb_host_claim_port(int bus, int hub, int port) "bus %d, hub addr %d, port %d"
 
 # hw/scsi-bus.c
 scsi_req_alloc(int target, int lun, int tag) "target %d lun %d tag %d"