missing space corrupted usb/probe output

Reference: /n/atom/patch/applied/usbprobeoutput
Date: Mon Mar 31 04:34:27 CES 2014
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/usb/usbd/dev.c	Mon Mar 31 04:34:21 2014
+++ /sys/src/cmd/usb/usbd/dev.c	Mon Mar 31 04:34:22 2014
@@ -220,7 +220,8 @@
 				s = seprint(s, se, " csp %#08ulx", ifc->csp);
 		}
 	}
-	devctl(d, "info %s" "csp %#08lux %s vid %#06x did %#06x %q %q",
+	*s = 0;
+	devctl(d, "info %s csp %#08lux %s vid %#06x did %#06x %q %q",
 		classname(ud->class), ud->csp,
 		buf, ud->vid, ud->did, ud->vendor, ud->product);
 	free(buf);