selftests/sgx: Use getauxval() to simplify test code

mainline inclusion
from mainline-v5.13-rc1
commit f33dece7
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4SIGI


CVE: NA

--------------------------------

Use the library function getauxval() instead of a custom function to get
the base address of the vDSO.

 [ bp: Massage commit message. ]

Intel-SIG: commit f33dece7 selftests/sgx: Use getauxval() to simplify test code
Backport for SGX Foundations support

Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lkml.kernel.org/r/20210314111621.68428-1-tianjia.zhang@linux.alibaba.com


Signed-off-by: Fan Du <fan.du@intel.com> #openEuler_contributor
Signed-off-by: Laibin Qiu <qiulaibin@huawei.com>
Reviewed-by: Bamvor Zhang <bamvor.zhang@suse.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>