Add regression test for USB enumeration.

MFC after:	1 week

tools/regression/usb/usb_enum.t

@@ -0,0 +1,30 @@
+#!/bin/sh
+# $FreeBSD$
+
+#
+# About:
+# This script implements a simple USB enumeration test
+#
+# Usage:
+# ./usb_enum.t ugenX.Y
+#
+
+echo "1..100"
+
+if [ "$1" = "" ]; then
+# First Root HUB
+DEV="ugen0.1"
+else
+# Custom device
+DEV="$1"
+fi
+
+for N in $(jot 100 1)
+do
+if [ -c /dev/$DEV ] && [ -r /dev/$DEV ] && usbconfig -d $DEV reset ; then
+echo "ok $N"
+else
+echo "not ok $N"
+fi
+done
+