tracefs: Remove kerneldoc from struct eventfs_file

tracefs: Remove kerneldoc from struct eventfs_file

The struct eventfs_file is a local structure and should not be parsed by
kernel doc. It also does not fully follow the kerneldoc format and is
causing kerneldoc to spit out errors. Replace the /** to /* so that
kerneldoc no longer processes this structure.

Also format the comments of the delete union of the structure to be a bit
better.

Link: https://lore.kernel.org/linux-trace-kernel/20230818201414.2729745-1-willy@infradead.org/
Link: https://lore.kernel.org/linux-trace-kernel/20230822053313.77aa3397@rorschach.local.home
Cc: Mark Rutland <mark.rutland@arm.com>
Reported-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>