Simplify the way outgoing work handler gets scheduled to send empty buffers
back to the firmware for use.  Also reduced the memory required for scheduling
this outgoing work, by using a single, per stream work object.
Signed-off-by: NAndy Walls <awalls@radix.net>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>