x86/efi: skip memattr table on kexec boot

efi_memattr_init() added a sanity check to avoid firmware caused corruption.
The check is based on efi memmap entry numbers, but kexec only takes the
runtime related memmap entries thus this caused many false warnings, see
below thread for details:

https://lore.kernel.org/all/20250108215957.3437660-2-usamaarif642@gmail.com/



Ard suggests to skip the efi memattr table in kexec, this makes sense because
those memattr fixups are not critical.

Fixes: 8fbe4c49 ("efi/memattr: Ignore table if the size is clearly bogus")
Cc: <stable@vger.kernel.org> # v6.13+
Reported-by: Breno Leitao <leitao@debian.org>
Reported-and-tested-by: Usama Arif <usamaarif642@gmail.com>
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>