drm/amdgpu: drop experimental flag on aldebaran

commit 3786a9bc upstream.

These have been at production level for a while. Drop
the flag.

Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>