amdgpu: A new option to run tests on render node

Tested:
1. As root, tests passed on primary.
2. As root, tests passed on render node.
   BO export/import test was skipped
3. As non-privileged user, tests failed on primary as expected.
4. As non-privileged user, tests passed on render node.
   BO export/import test was skipped

Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Alex Xie <AlexBin.Xie@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>