tracing: Add 'delete' file to remove multibuffer instances

Add a 'delete' file that is used to remove multibuffer instances.

Example:

  echo hello > /debug/tracing/instances/new
  ls /debug/tracing/instances
delete hello/ new
  echo hello > /debug/tracing/instances/delete
  ls /debug/tracing/instances
delete new

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
3 files changed