drm/radeon/kms: enable memory clock reading on legacy (V2)

V2: detect IGP cards (which don't have own memory)

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Acked-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
3 files changed