BUG/MINOR: stream: Fix test on SE_FL_ERROR on the wrong entity

There is a bug at begining of process_stream(). The SE_FL_ERROR flag is
tested against backend stream-connector's flags instead of its SE
descriptor's flags. It is an old typo, introduced when the stream-interfaces
were replaced by the conn-streams.

This patch must be backported as far as 2.6.
1 file changed