ACPI: remove cpumask_t usage

set_cpus_allowed() is on the way out; replace it with
set_cpus_allowed_ptr().

Reference: http://lkml.org/lkml/2008/11/6/448



Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>