drm/i915: Fix max link rate in intel_dp_mode_valid()

Consider the link rates reported by the sink via
DP_SUPPORTED_LINK_RATES when checking modes against the max link
rate.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Sonika Jindal <sonika.jindal@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --cc drivers/gpu/drm/i915/intel_dp.c
Simple merge

diff --cc drivers/gpu/drm/i915/intel_drv.h
Simple merge