arch: arm64: Add cpu_map to map cpu id and mpid

cpu_node_list does not hold the corrent mapping of cpu id and mpid when
core booting sequence does not follow the DTS cpu node sequence. This
will cause an issue that sgi cannot deliver to the right target.

Add the cpu_map array to hold the corrent mapping between cpu id and
mpid.

Signed-off-by: Jaxson Han <jaxson.han@arm.com>