drm/edid: Add CEA modes before inferred modes

Currently we're adding CEA modes after the inferred modes, which means
we might get multiple modes that are very close to each other, but
slightly different, which seems a bit silly. That's because duplicate
mode check that occurs when adding inferred modes would not consider
CEA modes as potential duplicates. Reverse the order so that CEA
modes get added before inferred modes, and are thus considered potential
duplicates.

Or as ajax put it on irc:
"< ajax> the point of the "pick a timing formula" heuristic was to
generate something the sink could _likely_ sink.  if it tells us
timings it can sink explicitly then second-guessing seems dumb."

Cc: Adam Jackson <ajax@redhat.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>