drm/vmwgfx: stop implementing init_mem_type v2

Instead just initialize the memory type parameters
before calling ttm_bo_init_mm.

v2: keep extra system domain handling

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/382082/