ASoC: SOF: compress: Remove byte offset computation

Byte offset is the offset in the ring buffer to the DSP
while posn_offset is an offset inside the stream_box where
we keep position information.

Reviewed-by: Paul Olaru <paul.olaru@oss.nxp.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Link: https://lore.kernel.org/r/20220817080529.10864-2-daniel.baluta@oss.nxp.com


Signed-off-by: Mark Brown <broonie@kernel.org>