coresight: trbe: Fix incorrect access of the sink specific data

The TRBE driver wrongly treats the aux private data as the TRBE driver
specific buffer for a given perf handle, while it is the ETM PMU's
event specific data. Fix this by correcting the instance to use
appropriate helper.

Cc: stable <stable@vger.kernel.org>
Fixes: 3fbf7f01 ("coresight: sink: Add TRBE driver")
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20210921134121.2423546-2-suzuki.poulose@arm.com


[Fixed 13 character SHA down to 12]
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>