ARM: kirkwood: convert uart0 to devicetree.

This uart is the primary console for the dreamplug.  Removed
kirkwood_uart0_init() call from board-dt.c.

Signed-off-by: Jason Cooper <jason@lakedaemon.net>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>