squashfs3: remove deprecated package/rootfs

[Peter: remove now unused BR2_DEPRECATED_SINCE_2010_05 symbol]
Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>