efi: Disable mirror feature during crashkernel

hulk inclusion
category: cleanup
bugzilla: https://gitee.com/openeuler/kernel/issues/I6WKXZ


CVE: NA

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If system have no mirrored memory or use crashkernel.high while
kernelcore=mirror is enabled in cmdline, during crashkernel,
there will be limited mirrored memory and this usually lead to
OOM.

To solve this problem, disable mirror feature during crashkernel.

Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>