cpu/apic: drop icc bus/bridge

After CPU hotplug has been converted to BUS-less hot-plug infrastructure,
the only function ICC bus performs is to propagate reset to LAPICs. However
LAPIC could be reset by registering its reset handler after all device are
initialized.
Do so and drop ~30LOC of not needed anymore ICCBus related code.

Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
Signed-off-by: Zhu Guihua <zhugh.fnst@cn.fujitsu.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>