Tune PaperMono fastest-mode LUT parameters

[zhenquan-yao]

Hi @lovyan03, I opened this PR to propose a LUT adjustment for PaperMono fastest mode.

In my testing with fastest mode, it helped reduce gray artifacts in white areas and faded black pixels after repeated refreshes, especially after shutdown or sleep. Feedback is welcome.

Summary

This change updates the LUT parameters used by the PaperMono display driver in fastest mode.

In fastest mode, after repeated refreshes, especially after around 20 to 30 refresh cycles, the display can show visible degradation after shutdown or sleep. White areas may appear light gray, and black pixels may become lighter. This change improves these issues by adjusting the waveform parameters used by the fastest-mode LUT.

This PR also corrects the reversed LUT color mapping comments for fastest mode.

During testing, similar degradation was also observed in factory_fast and factory_quality after repeated refreshes. These LUTs are not changed in this PR and still need further improvement.

Changes

• Tuned fastest-mode LUT parameters
• Corrected reversed LUT color mapping comments for fastest mode
• Improved fastest-mode display quality after repeated refreshes, especially after 20 to 30 refresh cycles
• Reduced light-gray artifacts in white areas after shutdown or sleep in fastest mode
• Reduced fading of black pixels after shutdown or sleep in fastest mode
• Left factory_fast and factory_quality unchanged, although similar issues were observed there during testing

Testing

• Repeated refresh testing was performed in fastest mode
• In fastest mode, the issue became more noticeable after approximately 20 to 30 refresh cycles before the LUT adjustment
• After the waveform adjustment, fastest mode showed fewer light-gray artifacts in white areas after shutdown or sleep, and less fading of black pixels
• factory_fast and factory_quality were also checked and showed similar degradation after repeated refreshes, but their LUT parameters were not modified in this change