ARM: 6776/1: mach-ux500: activate fix for errata 753970

This applies errata fix 753970 for all ux500 platforms. All
current ASICs suffer from this. If the problem is resolved in
later ASICs, the errata selection can be pushed down to other
Kconfig options.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>