arm64/mpam: resctrl: Remove unnecessary CONFIG_ARM64

hulk inclusion
category: feature
bugzilla: 34278
CVE: NA

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Code in resctrlfs.c is not shared with x86 RDT currently, but may be
updated to support both in the future, so remove unrelated CONFIG for
now to make code clearer.

Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Reviewed-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>