ASoC: SOF: trace: Simplify count adjustment in trace_read

The first count check and fixup against "buffer - lpos" can be removed as
we will do the adjustment later against the "avail" in
sof_dfsentry_trace_read()

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/20220128120627.18443-1-peter.ujfalusi@linux.intel.com


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