svm: Change svm to modules and remove unused functions

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


CVE: NA
-------------------

Change svm to modules by default.
Remove get mem info functions, users can get the meminfo from procfs.

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