x86: fix build error with post-merge of tip/cpus4096 and rr-for-ingo/master.

Ingo Molnar wrote:

> allyes64 build failure:
>
> arch/x86/kernel/io_apic.c: In function ‘set_ir_ioapic_affinity_irq_desc’:
> arch/x86/kernel/io_apic.c:2295: error: incompatible type for argument 2 of
> ‘migrate_ioapic_irq_desc’
> arch/x86/kernel/io_apic.c: In function ‘ir_set_msi_irq_affinity’:
> arch/x86/kernel/io_apic.c:3205: error: incompatible type for argument 2 of
> ‘set_extra_move_desc’
> make[1]: *** wait: No child processes.  Stop.

Here's a small patch to correct the build error with the post-merge tree.
Built and boot-tested.  I'll will reset the follow on patches in my brand
new git tree to accommodate this change.

Fix two references in io_apic.c that were incorrect.

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>