openeuler_defconfig: set CONFIG_NODES_SHIFT to 8 for both x86_64/ARM64

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8UT5S


CVE: NA

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There is no extra bit in pageflags for new flag on x86_64. Since 256 nodes
is enough for x86_64, reduce CONFIG_NODES_SHIFT to 8 to obtain two unused
bits on x86_64.

On arm64, 128 node is not enough, so raise CONFIG_NODES_SHIFT to 8.

Signed-off-by: Liu Shixin <liushixin2@huawei.com>