Convert EDID code to use defines and scrub against CEA-861-D

Recent code review of change recommended using defines for the EDID offsets
reather than just the numeric offsets. This does that conversion using
the CEA-861-D standard as the guideline. In addition the standard document
shows a few places where the fields have different meanings from the
previous understanding, and these have been fixed.

This CL only changes the edid_utils code. Fixes in the ch7036_monitor will
be added as a future CL.

Testing uses the ch7036_debug -n E to dump the test EDIDs. Comparing the output
before and after the change reflects the fixed default-GTF flag location
and the improved formatting for the default underscan reporting and the
use of byte 3 of the short audio descriptor for codes 9 to 15.

BUG=None
TEST=Compare test EDID decoding as described

Change-Id: Ifabc8541ebc88367793e4d4cef784b1511a4eec6
Reviewed-on: http://gerrit.chromium.org/gerrit/2859
Reviewed-by: Todd Broch <tbroch@chromium.org>
Tested-by: Mark Hayter <mdhayter@chromium.org>
2 files changed