edid-decode: Incorrect decoding of CTA extension if it does not contain padding bytes

[Pavel Kuzmin <kuzkin@xxxxxxxxx>]

Hello


If in the EDID CTA extension the last 18 byte DTD block ends
immediately before the checksum byte (no padding bytes) then the last
DTD block is not processed and a failure is displayed "Padding:
CTA-861 padding contains non-zero bytes."

e.g. https://github.com/linuxhw/EDID/blob/master/Digital/Acer/ACR0549/42BFE4422CEF


Regards,
Pavel