xen: rename dom0_op to platform_op

The dom0_op hypercall has been renamed to platform_op since Xen 3.2,
which is ancient, and modern upstream Linux kernels cannot run as dom0
and it anymore anyway.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

xen / ACPI: notify xen when reduced hardware sleep is available

Use the acpi_os_prepare_extended_sleep() callback to notify xen
to make use of the reduced hardware sleep functionality

The xen hypervisor change underlying this is commit 62d1a69
("ACPI: support v5 (reduced HW) sleep interface") on the master
branch of git://xenbits.xen.org/xen.git.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Ben Guthro <benjamin.guthro@citrix.com>
Acked-by: Konrad Wilk <konrad.wilk@oracle.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

xen/acpi/sleep: Enable ACPI sleep via the __acpi_os_prepare_sleep

Provide the registration callback to call in the Xen's
ACPI sleep functionality. This means that during S3/S5
we make a hypercall XENPF_enter_acpi_sleep with the
proper PM1A/PM1B registers.

Based of Ke Yu's <ke.yu@intel.com> initial idea.
[ From http://xenbits.xensource.com/linux-2.6.18-xen.hg
change c68699484a65 ]

[v1: Added Copyright and license]
[v2: Added check if PM1A/B the 16-bits MSB contain something. The spec
only uses 16-bits but might have more in future]
Signed-off-by: Liang Tang <liang.tang@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>