The previous check to block capture port streaming before output port
was incorrect and caused some valid usecase to fail. While removing that
check allows capture port to enter streaming independently, it also
introduced firmware errors due to premature queuing of DPB buffers
before the firmware session was fully started which happens only when
streamon is called on output port.
Fix this by deferring DPB buffer queuing to the firmware until both
capture and output are streaming and state is 'STREAMING'.