ACPI: processor: Don't setup cpu idle handler when we do not want them.

ACPI: processor: Don't setup cpu idle handler when we do not want them.

This patch inhibits processing of the CPU idle handler if it is not
set to the appropiate one. This is needed by the Xen processor driver
which, while still needing processor details, wants to use the default_idle
call (which makes a yield hypercall).

Signed-off-by: Yu Ke <ke.yu@intel.com>
Signed-off-by: Tian Kevin <kevin.tian@intel.com>
Signed-off-by: Tang Liang <liang.tang@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>