drm/radeon: OLAND boards don't have VCE

Disable it on those boards.  No functional change, this just
removes the message about VCE failing to initialize.

Bug: https://bugzilla.kernel.org/show_bug.cgi?id=197327
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>