drm/edid: Move dvi_dual/max_tmds_clock parsing out from drm_edid_to_eld()

drm_edid_to_eld() is just mean to cook up the ELD for the audio driver,
so having it parse non-audio related stuff seems just wrong, and
potentially could lead to that information not being even filled out
if the function doesn't even get called. Let's move that stuff to the
place where we parse the color formats and whatnot from the CEA ext
block.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1475070703-6435-9-git-send-email-ville.syrjala@linux.intel.com