drm/stm: ltdc: add support for CRC hashing feature

This patch adds the CRC hashing feature supported by some recent hardware
versions of the LTDC. This is useful for test suite such as IGT-GPU-tools
[1] where a CRTC output frame can be compared to a test reference frame
thanks to their respective CRC hash.

[1] https://cgit.freedesktop.org/drm/igt-gpu-tools



Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
Acked-by: Yannick Fertre <yannick.fertre@foss.st.com>
Signed-off-by: Philippe Cornu <philippe.cornu@foss.st.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220211104620.421177-1-raphael.gallais-pou@foss.st.com