efi: Fix efi_find_mirror redefine in x86

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


CVE: NA

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Commit cc3d801f ("efi: Make efi_find_mirror() public") add
efi_find_mirror() defination into linux/efi.h, but forget to
drop this in arch/x86/include/asm/efi.h, kill it.

Fixes: cc3d801f ("efi: Make efi_find_mirror() public")
Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>