drm/atomic-helpers: Saner encoder/crtc callbacks
For historical reasons going all the way back to how the Xrandr code
was implemented the semantics of the callbacks used to enable/disable
crtcs and encoders are ... interesting.
But with atomic helpers all that complexity has been binned, with only
a well-defined on/off action left. Unfortunately the names stuck.
Let's fix that by adding enable/disable hooks every, make them the
preferred variant for atomic and update documentations.
Later on we add debug warnings when drivers have deprecated hooks. But
while everything is in-flight with lots of drivers converting to
atomic that's a bit too much - better wait for things to settle a bit
first.
v2: Fix kerneldoc, reported by Wu Fengguang.
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>