[PATCH] x86-64: don't use set_irq_regs()

We don't need to setup _irq_regs in smp_xxx_interrupt (except apic timer).
These handlers run with irqs disabled and do not call functions which need
"struct pt_regs".

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@suse.de>
Acked-By: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>