soc: versatile: Add terminating entry for realview_soc_of_match

The of_device_id table is supposed to be zero-terminated.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>