We currently define macros referring to cpu_data if CONFIG_SMP is
defined, but only include the declaration if CONFIG_NUMA is defined.

Fixes: 541cc394 ("sparc: fix a building error reported by kbuild")
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Acked-by: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>