drm: Nuke drm_atomic_helper_plane_set_property

drm: Nuke drm_atomic_helper_plane_set_property

It's dead code, the core handles all this directly now. This also
allows us to unexport drm_atomic_plane_set_property.

Signed-off-by: Daniel Vetter <[email protected]>
Cc: Liviu Dudau <[email protected]>
Cc: Brian Starkey <[email protected]>
Cc: Mali DP Maintainers <[email protected]>
Cc: Boris Brezillon <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Sean Paul <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Inki Dae <[email protected]>
Cc: Joonyoung Shim <[email protected]>
Cc: Seung-Woo Kim <[email protected]>
Cc: Kyungmin Park <[email protected]>
Cc: Kukjin Kim <[email protected]>
Cc: Krzysztof Kozlowski <[email protected]>
Cc: Ben Skeggs <[email protected]>
Cc: Tomi Valkeinen <[email protected]>
Cc: Laurent Pinchart <[email protected]>
Cc: Benjamin Gaignard <[email protected]>
Cc: Vincent Abriou <[email protected]>
Cc: Yannick Fertre <[email protected]>
Cc: Philippe Cornu <[email protected]>
Cc: Jyri Sarha <[email protected]>
Cc: "Ville Syrjälä" <[email protected]>
Cc: Rongrong Zou <[email protected]>
Cc: Shawn Guo <[email protected]>
Cc: Alexey Brodkin <[email protected]>
Cc: Eric Engestrom <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Rob Clark <[email protected]>
Cc: Archit Taneja <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Thomas Hellstrom <[email protected]>
Cc: Maxime Ripard <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Reviewed-by: Archit Taneja <[email protected]>
Acked-by: Philippe Cornu <[email protected]>
Tested-by: Philippe Cornu <[email protected]>
Acked-by: Liviu Dudau <[email protected]>
Acked-by: Vincent Abriou <[email protected]>
Reviewed-by: Maarten Lankhorst <[email protected]>
Reviewed-by: Laurent Pinchart <[email protected]>