mpegtspacketizer: be more tolerant when parsing the adaptation field
According to the specification, the adaptation field length must be 183 if there is no payload data and < 183 if the packet contains an adaptation field and payload data.
Unfortunately some payloaders always set the flag for payload data, even if the adaptation field length is 183.
Don't return with an error in this case. Clear the payload data flag instead and parse the adaptation field as usual. This avoids visual artefacts for such streams.