drm/i915: Workaround ICL CSC_MODE sticky arming

Unlike SKL/GLK the ICL CSC unit suffers from a new issue where
CSC_MODE arming is sticky. That is, once armed it remains armed
causing the CSC coeff/offset registers to become effectively
self-arming.

CSC coeff/offset registers writes no longer disarm the CSC,
but fortunately register read still do. So we can use that
to disarm the CSC unit once the registers for the current
frame have been latched. This avoid s the self-arming behaviour
from persisting into the next frame's .color_commit_noarm()
call.

Cc: <[email protected]> #v5.19+
Cc: Manasi Navare <[email protected]>
Cc: Drew Davenport <[email protected]>
Cc: Imre Deak <[email protected]>
Cc: Jouni Högander <[email protected]>
Fixes: d13dde449580 ("drm/i915: Split pipe+output CSC programming to noarm+arm pair")
Signed-off-by: Ville Syrjälä <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Reviewed-by: Imre Deak <[email protected]>

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