drm/i915/dp: Handle Synaptics DSC throughput link-bpp quirk

drm/i915/dp: Handle Synaptics DSC throughput link-bpp quirk

Handle the DSC pixel throughput quirk, limiting the compressed link-bpp
value for Synaptics Panamera branch devices, working around a
blank/unstable output issue observed on docking stations containing
these branch devices, when using a mode with a high pixel clock and a
high compressed link-bpp value.

For now use the same mode clock limit for RGB/YUV444 and YUV422/420
output modes. This may result in limiting the link-bpp value for a
YUV422/420 output mode already at a lower than required mode clock.

v2: Apply the quirk only when DSC is enabled.
v3 (Ville):
- Move adjustment of link-bpp within the already existing is_dsc
  if branch.
- Add TODO comment to move the HW revision check as well to the
  DRM core quirk table.
v4:
- Fix incorrect fxp_q4_from_int(INT_MAX) vs. INT_MAX return value
  from dsc_throughput_quirk_max_bpp_x16().

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reported-by: Vidya Srinivas <vidya.srinivas@intel.com>
Reported-and-tested-by: Swati Sharma <swati2.sharma@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20250930182450.563016-7-imre.deak@intel.com