drm/i915: Introduce crtc_state->{pre,post}_csc_lut

drm/i915: Introduce crtc_state->{pre,post}_csc_lut

Add an extra remapping step between the logical state of the LUTs
(hw.(de)gamma_lut) as specified via uapi/bigjoiner copy vs.
the actual state of the LUTs programmed into the hardware.

With this we should be finally able finish the (de)gamma
readout/state checker support for the remaining platforms
(ilk-skl) where the same hardware LUT can be positioned
either before or after the pipe CSC unit. Where we position
it depends on factors such as presence of the logical degamma
LUT, RGB vs. YCbCr output, full vs. limited RGB quantization
range.

Without the extra remapping step the state readout doesn't
really know whether the LUT read from the hardware is the
degamma or gamma LUT, and so we is unable to accurately store
it into our crtc state. With the remapping step we know
exactly where to put it given the order of the LUT vs. CSC
in the hardware state.

Only the initial hw->uapi state readout done during driver
load/resume still has the problem of not really knowing
what to do with the LUT(s). But we can just assume 1:1
mapping there and let subsequent commits fix things up.

Another benefit is that we now have a place for purely
internal LUTs, without complicating the bigjoiner uapi->hw
copy logic. This should prove useful for streamlining
glk degamma LUT handling.

Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221024161514.5340-3-ville.syrjala@linux.intel.com