xen: Re-upload processor PM data to hypervisor after S3 resume (v2)

Upon resume, it was found that ACPI C-states were missing from non-boot CPUs.
This change registers a syscore_ops handler for this case, and re-uploads the
PM information to the hypervisor to properly reset the C-state on these
processors.

v2:
v1 did not go through the check_acpi_ids() code-path, and missed some cases when
xen was running with the dom0_max_vcpus= command line parameter.

Signed-Off-By: Ben Guthro <benjamin.guthro@citrix.com>
[v3: Ate some tabs, s/printk/pr_info/]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>