drm/ttm: drop type manager has_type

under driver control, this flag isn't needed anymore,
remove the API that used to access it, and consoldiate
with the used api.

Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200804025632.3868079-56-airlied@gmail.com