drm/i915/dp: Reject HBR3 when sink doesn't support TPS4

drm/i915/dp: Reject HBR3 when sink doesn't support TPS4

According to the DP spec TPS4 is mandatory for HBR3. We have
however seen some broken eDP sinks that violate this and
declare support for HBR3 without TPS4 support.

At least in the case of the icl Dell XPS 13 7390 this results
in an unstable output.

Reject HBR3 when TPS4 supports is unavailable on the sink.

v2: Leave breadcrumbs in dmesg to avoid head scratching (Jani)

Cc: stable@vger.kernel.org
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/5969
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250306210740.11886-1-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>