x86/smp: PM/hibernate: Split arch_resume_nosmt()

Move the inner part of the arch_resume_nosmt() code into a separate
function called arch_cpu_rescan_dead_smt_siblings(), so it can be
used in other places where "dead" SMT siblings may need to be taken
online and offline again in order to get into deep idle states.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Link: https://patch.msgid.link/3361688.44csPzL39Z@rjwysocki.net


[ rjw: Prevent build issues with CONFIG_SMP unset ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>