irq: make ht irq_desc more numa aware

Try to get irq_desc on the same node as create_irq_nr().

[ Impact: optimization, make HT IRQs more NUMA-aware ]

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
LKML-Reference: <49F655B6.8020109@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>