USB: kobil: fix memory leak

An urb transfer buffer is allocated at every open but was never freed.

This driver is a bit of a mess...

Cc: stable <stable@kernel.org>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/serial/kobil_sct.c b/drivers/usb/serial/kobil_sct.c
index c113a2a..bd5bd85 100644
--- a/drivers/usb/serial/kobil_sct.c
+++ b/drivers/usb/serial/kobil_sct.c
@@ -345,7 +345,8 @@
 
 	/* FIXME: Add rts/dtr methods */
 	if (port->write_urb) {
-		usb_kill_urb(port->write_urb);
+		usb_poison_urb(port->write_urb);
+		kfree(port->write_urb->transfer_buffer);
 		usb_free_urb(port->write_urb);
 		port->write_urb = NULL;
 	}