[PATCH] USB ATM: avoid oops on bind failure; plug memory leak

Zero the entire instance, not just the struct usbatm_data head.
Make sure the just allocated urb is freed if we fail to allocate
a buffer.  Based on a patch by Stanislaw W. Gruszka.

Signed-off-by: Duncan Sands <baldrick@free.fr>
Acked-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>