x86: Rename incorrectly named parameter of numa_cpu_node()

numa_cpu_node() prototype in numa_32.h has wrongly named
parameter @apicid when it actually takes the CPU number.

Change it to @cpu.

Reported-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
LKML-Reference: <20110131155905.GM7459@htj.dyndns.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>