efi: Stub mirrored_kernelcore if CONFIG_HAVE_MEMBLOCK_NODE_MAP is not enabled

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4SK3S


CVE: NA

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Stub mirrored_kernelcore if CONFIG_HAVE_MEMBLOCK_NODE_MAP is not enabled.
If CONFIG_HAVE_MEMBLOCK_NODE_MAP is disabled, mirrored_kernelcore in
efi_find_mirror() will be undeclared and this will lead to compile problem.

Fixes: d7421c3f ("efi: Disable mirror feature if kernelcore is not spcified")
Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>