x86: increase size of APICID

Increase the number of bits in an apicid from 8 to 32.

By default, MP_processor_info() gets the APICID from the
mpc_config_processor structure. However, this structure limits
the size of APICID to 8 bits. This patch allows the caller of
MP_processor_info() to optionally pass a larger APICID that will
be used instead of the one in the mpc_config_processor struct.

Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>