edid-decode: fix DTD and non-zero borders

EDID 1.3 and 1.4 have conflicting definitions about how to
interpret borders and blanking in a DTD. And actual EDIDs interpret
different from both specs.

Follow what EDIDs do, and add a warning that non-zero borders in a
DTD is not recommended.

Signed-off-by: Hans Verkuil <[email protected]>
1 file changed