drm/vmwgfx: Remove busy_places

Unused since commit a78a8da5
("drm/ttm: replace busy placement with flags v6")

Signed-off-by: Ian Forbes <ian.forbes@broadcom.com>
Reviewed-by: Martin Krastev <martin.krastev@broadcom.com>
Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250108201355.2521070-1-ian.forbes@broadcom.com