highbank: Unconditionally require l2x0 L2 cache controller support

highbank: Unconditionally require l2x0 L2 cache controller support

If running in the Normal World on a TrustZone-enabled SoC, Linux
does not have complete control over the L2 cache controller
configuration.  The kernel cannot work reliably on such platforms
without the l2x0 cache support code built in.

This patch unconditionally enables l2x0 support for the Highbank
SoC.

Thanks to Rob Herring for this suggestion.  [1]

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2011-November/074495.html

Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Rob Herring <rob.herring@calxeda.com>