ARM: ux500: select L2X0 cache on ux500

The cache controller needs to be enabled for the
cortex-a9 specific errata that are also selected
to work.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>