ARM: 8660/1: shmobile: r7s72100: Enable L2 cache

Even though L2C is specified in the DT, you still need to add the aux
settings in the machine_desc.

Signed-off-by: Chris Brandt <chris.brandt@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>