PM: hibernate: Use kernel_can_power_off()

PM: hibernate: Use kernel_can_power_off()

Use new kernel_can_power_off() API instead of legacy pm_power_off global
variable to fix regressed hibernation to disk where machine no longer
powers off when it should because ACPI power driver transitioned to the
new sys-off based API and it doesn't use pm_power_off anymore.

Fixes: 98f30d0ecf79 ("ACPI: power: Switch to sys-off handler API")
Tested-by: Ken Moffat <zarniwhoop@ntlworld.com>
Reported-by: Ken Moffat <zarniwhhop@ntlworld.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>