media: coda: retire coda_buf_is_end_of_stream

Using the output queue sequence counter to determine the last buffer to
be encoded or decoded always was fragile at best. Now that we have the
last buffer flag propagating from the output queue to the capture queue
correctly, this is not needed anymore.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>