fsnotify: move mask out of struct fsnotify_event

Common fsnotify_event helpers have no need for the mask field.
It is only used by backend code, so move the field out of the
abstract fsnotify_event struct and into the concrete backend
event structs.

This change packs struct inotify_event_info better on 64bit
machine and will allow us to cram some more fields into
struct fanotify_event_info.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/notify/inotify/inotify.h

@@ -5,6 +5,7 @@
 
 struct inotify_event_info {
 	struct fsnotify_event fse;
+	u32 mask;
 	int wd;
 	u32 sync_cookie;
 	int name_len;