scsi: scsi_debug: Stop printing extra function name in debug logs

scsi: scsi_debug: Stop printing extra function name in debug logs

The driver defines as follows pr_fmt:

  #define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__

...meaning that we already get the function name added in any debug
statements.

Remove using of __func__ in debug logs to avoid the duplication.

For instances of where the function name was being printed, add some
verbose comment to avoid using "" (which would be a bit silly).

It would be nicer to stop using pr_fmt(), but that would mean rewriting
approx 100 debug statements to have a sensible and clear message.

Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://patch.msgid.link/20251113133645.2898748-2-john.g.garry@oracle.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>