arm64: remove page granularity limitation from KFENCE

hulk inclusion
category: bugfix
bugzilla: 181005 https://gitee.com/openeuler/kernel/issues/I4DDEL



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Currently if KFENCE is enabled in arm64, the entire linear map will be
mapped at page granularity which seems overkilled. Actually only the
kfence pool requires to be mapped at page granularity. We can remove the
restriction from KFENCE and force the linear mapping of the kfence pool
at page granularity later in arch_kfence_init_pool().

Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>

Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>