svm: add set l2 cache read count functions

ascend inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4JMM0


CVE: NA

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implement set l2 cache read count, svm drv will
modify the page table pte to set read count for
smmu

Signed-off-by: Lijun Fang <fanglijun3@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>