x2APIC: simplify resume

x2APIC: simplify resume

There's no need to save and restore the IO-APIC entries, the entries
prior to suspension have already been saved by ioapic_suspend, and
will be restored by ioapic_resume. Note that at the point where
resume_x2apic gets called the IO-APIC has not yet resumed, and hence
all entries should be masked.

Note this shouldn't introduce any functional change.

Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Tested-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Release-acked-by: Juergen Gross <jgross@suse.com>