x86_32: apic/summit_32, fix cpu_mask_to_apicid

Perform same-cluster checking even for masks with all (nr_cpu_ids)
bits set and report correct apicid on success instead.

While at it, convert it to for_each_cpu and newer cpumask api.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>