mach-ux500: ab5500 platform code added

This patch adds the platform part needed to get the
ab5500-core driver started.

Signed-off-by: Mattias Wallin <mattias.wallin@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>