drm: Check against color expansion in drm_mm_reserve_node()

Use the color_adjust callback when reserving a node to check if
inserting a node into this hole requires any additional space, and so if
that space then conflicts with an existing allocation.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161123141118.23876-2-chris@chris-wilson.co.uk