sw64: fix support for qemu boards without IOR:SMP_INFO

Sunway inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I73KSB



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It failed to run on earlier qemu boards because absence of the new
IOR:SMP_INFO. This patch does some compatibility work.

Signed-off-by: He Sheng <hesheng@wxiat.com>
Reviewed-by: Cui Wei <cuiwei@wxiat.com>
Signed-off-by: Gu Zitao <guzitao@wxiat.com>