coresight: Update comments for removing cs_etm_find_snapshot()

Commit 2f01c200 ("perf cs-etm: Remove callback cs_etm_find_snapshot()")
has removed the function cs_etm_find_snapshot() from the perf tool in the
user space, now CoreSight trace directly uses the perf common function
__auxtrace_mmap__read() to calcualte the head and size for AUX trace data
in snapshot mode.

This patch updates the comments in drivers to make them generic and not
stick to any specific function from perf tool.
Signed-off-by: NLeo Yan <leo.yan@linaro.org>
Link: https://lore.kernel.org/r/20210912125748.2816606-3-leo.yan@linaro.orgSigned-off-by: NSuzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: NMathieu Poirier <mathieu.poirier@linaro.org>

drivers/hwtracing/coresight/coresight-etb10.c

@@ -557,9 +557,8 @@ static unsigned long etb_update_buffer(struct coresight_device *csdev,
 
 	/*
 	 * In snapshot mode we simply increment the head by the number of byte
-	 * that were written.  User space function  cs_etm_find_snapshot() will
-	 * figure out how many bytes to get from the AUX buffer based on the
-	 * position of the head.
+	 * that were written.  User space will figure out how many bytes to get
+	 * from the AUX buffer based on the position of the head.
 	 */
 	if (buf->snapshot)
 		handle->head += to_read;

drivers/hwtracing/coresight/coresight-tmc-etf.c

@@ -546,9 +546,8 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
 
 	/*
 	 * In snapshot mode we simply increment the head by the number of byte
-	 * that were written.  User space function  cs_etm_find_snapshot() will
-	 * figure out how many bytes to get from the AUX buffer based on the
-	 * position of the head.
+	 * that were written.  User space will figure out how many bytes to get
+	 * from the AUX buffer based on the position of the head.
 	 */
 	if (buf->snapshot)
 		handle->head += to_read;

drivers/hwtracing/coresight/coresight-tmc-etr.c

@@ -1556,9 +1556,8 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
 
 	/*
 	 * In snapshot mode we simply increment the head by the number of byte
-	 * that were written.  User space function  cs_etm_find_snapshot() will
-	 * figure out how many bytes to get from the AUX buffer based on the
-	 * position of the head.
+	 * that were written.  User space will figure out how many bytes to get
+	 * from the AUX buffer based on the position of the head.
 	 */
 	if (etr_perf->snapshot)
 		handle->head += size;