concat: dot not reset pad states too early
concat: dot not reset pad states too early

Resetting the flushing state of the pads at the end of the
PAUSED_TO_READY transition will make pads handle serialized
queries again which will wait for non-active pads and might
cause deadlocks when stopping the pipeline.

Move the reset to the READY_TO_PAUSED instead.

https://bugzilla.gnome.org/show_bug.cgi?id=752623

StreamUtils/gstreamer,centricular/gstreamer,jpxiong/gstreamer,krichter722/gstreamer,StreamUtils/gstreamer,StreamUtils/gstreamer,StreamUtils/gstreamer,centricular/gstreamer,centricular/gstreamer,StreamUtils/gstreamer,centricular/gstreamer,krichter722/gstreamer,krichter722/gstreamer,jpxiong/gstreamer,centricular/gstreamer,jpxiong/gstreamer,jpxiong/gstreamer,krichter722/gstreamer,jpxiong/gstreamer,krichter722/gstreamer