memhp: move GPE handler_E03 into build_memory_hotplug_aml()

>From this patch all the memory hotplug related AML
bits are consolidated in one place within DSTD.
Follow up patches will utilize that to simplify
memory hotplug related C/AML code.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>