fanotify: remove reference to fill_event_metadata()

fill_event_metadata() was removed in commit bb2f7b45
("fanotify: open code fill_event_metadata()")

Link: https://lore.kernel.org/r/20200512181836.405879-1-fabf@skynet.be


Signed-off-by: Fabian Frederick <fabf@skynet.be>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>