drm/i915: Parse max HDMI TMDS clock from VBT

Starting from version 204 VBT can specify the max TMDS clock we are
allowed to use with HDMI ports. Parse that information and take it
into account when filtering modes and computing a crtc state.

Also take the opportunity to sort the platform check if ladder
from new to old.

v2: Add defines for the values into intel_vbt_defs.h (Jani)
    Don't fall back to 0 silently for unknown values (Jani)
    Skip the debug print for the 0 case (Jani)

Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171030145702.23662-1-ville.syrjala@linux.intel.com