selftests/sgx: Rename 'eenter' and 'sgx_call_vdso'

mainline inclusion
from mainline-v5.14-rc1
commit 6a7171b8
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4SIGI


CVE: NA

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

Rename symbols for better clarity:

* 'eenter' might be confused for directly calling ENCLU[EENTER].  It does
  not.  It calls into the VDSO, which actually has the EENTER instruction.
* 'sgx_call_vdso' is *only* used for entering the enclave.  It's not some
  generic SGX call into the VDSO.

Intel-SIG: commit 6a7171b8 selftests/sgx: Rename 'eenter' and 'sgx_call_vdso'
Backport for SGX Foundations support

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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>