ARM: ux500: Initial Device Tree support for Snowball

This provides very basic Device Tree support for ST-Ericsson's
low-cost development platform, Snowball. If Device Tree for
ux500 is enabled and the correct board is configured within the
Device Tree blob, the correct *_init_machine() will be called.

This patch is based on some original work completed by:
  Niklas Hernaeus <niklas.hernaeus@linaro.org>

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Niklas Hernaeus <niklas.hernaeus@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>