Kexec disables outer cache before jumping to reboot code, but it doesn't
flush it explicitly. Flush is done implicitly inside of l2x0_disable().
But some SoC's override default .disable handler and don't flush cache.
This may lead to a corrupted memory during Kexec reboot on these
platforms.

This patch adds cache flush inside of OMAP4 and Highbank outer_cache.disable()
handlers to make it consistent with default l2x0_disable().
Acked-by: NRob Herring <rob.herring@calxeda.com>
Acked-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NTaras Kondratiuk <taras.kondratiuk@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>