inotify: Don't force FS_IN_IGNORED

According to Amir:

"FS_IN_IGNORED is completely internal to inotify and there is no need
to set it in i_fsnotify_mask at all, so if we remove the bit from the
output of inotify_arg_to_mask() no functionality will change and we will
be able to overload the event bit for FS_ERROR."

This is done in preparation to overload FS_ERROR with the notification
mechanism in fanotify.

Link: https://lore.kernel.org/r/20211025192746.66445-8-krisman@collabora.comSuggested-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/notify/inotify/inotify_user.c

@@ -94,10 +94,10 @@ static inline __u32 inotify_arg_to_mask(struct inode *inode, u32 arg)
 	__u32 mask;
 
 	/*
-	 * Everything should accept their own ignored and should receive events
-	 * when the inode is unmounted.  All directories care about children.
+	 * Everything should receive events when the inode is unmounted.
+	 * All directories care about children.
 	 */
-	mask = (FS_IN_IGNORED | FS_UNMOUNT);
+	mask = (FS_UNMOUNT);
 	if (S_ISDIR(inode->i_mode))
 		mask |= FS_EVENT_ON_CHILD;