This reverts commit 7ee686034b8b "drm/i915/dp: Ratelimit DP aux timeout
messages" as although it successfully squelches the debug messages, when
it does so it generates a warning instead. CI lights up orange with all
the warnings!
In its current incarnation DRM_DEBUG_RATELIMITED is not usable for us,
and we need to first teach lib/ratelimit.c not to warn when used for
debug messages.