crash on shutdown on rs/6000 powerpc

[Joel Schopp]

> [c00000003f923c40] c00000000003bff4 .xics_migrate_irqs_away+0x3c/0x20c
> [c00000003f923d00] c000000000040d54 .pseries_cpu_disable+0x98/0xb4
> [c00000003f923d80] c000000000028e4c .__cpu_disable+0x44/0x58
> [c00000003f923df0] c00000000007e204 .take_cpu_down+0x34/0x60
> [c00000003f923e70] c00000000008ba3c .do_stop+0x144/0x1e4
> [c00000003f923f00] c00000000006fd74 .kthread+0x78/0xc4
> [c00000003f923f90] c0000000000272a8 .kernel_thread+0x4c/0x68
> 
> I don't have time tonight or tomorrow to track this down further.  I'm
> taking the kids to the coast tommorow. :)

This looks like the problem Olof and Milton sent out patches to fix.  The 
Power3 shouldn't be doing cpu hotplug.