selftests: x86: test_vsyscall: conform test to TAP format output

Conform the layout, informational and status messages to TAP. No
functional change is intended other than the layout of output messages.
Add more logic code to skip the tests if particular configuration isn't
available to make sure that either we skip each test or mark it pass/fail.
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>