[PATCH] USB: Resource leak fix for whiteheat driver

We may return from drivers/usb/serial/whiteheat.c::whiteheat_attach()
without freeing `result' if we leave via the no_firmware: label.

Spotted by the coverity checker as #670

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>