coresight: Fix duplicate and abnormal stop issues of PCIE sw path

Compare with sysfs buffer size instead of drvdata size to avoid the
duplicate data issue. Need to compare with the actual data size as
the data size could be smaller than the PCIE block size.

Change-Id: I45175b57a9154cbfb96946d424b8474a6a69213f
Signed-off-by: Mao Jinlong <quic_jinlmao@quicinc.com>