drm/legacy: move init/destroy of struct members into legacy file

This introduces drm_legacy_misc.c as a place for some misc legacy code,
eventually I want to give the option to remove this from the build.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
4 files changed