x86/kernel/traps.c: fix trace_die_notifier return value

x86/kernel/traps.c: fix trace_die_notifier return value

When triggering a int3 directly, the trace_die_notifier() actually returns 1
(whereas all other notifiers return 0), and that 1 value was being interpreted
as an indicator that DTrace handled the trap and that emulation is needed.  The
codei, from that point on, took a branch that is only to be used when the trap
occurs in kernel code, which is not good when it was actually triggered from
userspace.

OraBug: 27895315
CVE: CVE-2018-8897

Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>