ARM: ux500: New DT:ed snowball_platform_devs for one-by-one device enablement

During Device Tree enablement it is necessary to remove snowball_<device>*
platform_data segments one at at time, as and when particular devices are
DT enabled. This patch provides a temporary solution. Once this new struct
is empty it will be removed again.

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