debugfs: move ->automount into debugfs_inode_info

... and don't bother with debugfs_fsdata for those.  Life's
simpler that way...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20250112080705.141166-2-viro@zeniv.linux.org.uk


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>