drm: Make drm_atomic_helper.h standalone includible
drm: Make drm_atomic_helper.h standalone includible

This header uses a bunch of declarations from the drm/drm_crtc.h header,
so make sure to include that as well so that drm_atomic_helper.h can be
included standalone.

Reviewed-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>
Signed-off-by: Thierry Reding <3055038c414aef68bf32c33b8118623e7554e0f2@nvidia.com>
Signed-off-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs