eventfs: Fix kernel-doc comments to functions

This commit fix kernel-doc style comments with complete parameter
descriptions for the lookup_file(),lookup_dir_entry() and
lookup_file_dentry().

Link: https://lore.kernel.org/linux-trace-kernel/20240322062604.28862-1-yang.lee@linux.alibaba.com

Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>