tests/amdgpu: bypass UVD CS tests on raven

raven doesn't support UVD decode

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Xiaojie Yuan <Xiaojie.Yuan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>