ARM: kirkwood: fdt: absorb kirkwood_init()

We need to absorb kirkwood_init() into kirkwood_dt_init() so that as we
convert drivers, we can remove the platform call, eg
kirkwood_rtc_init().  This maintains compatibility with non-fdt
configurations because they still call kirkwood_init() in common.c.

As drivers are converted, we will reinstate the 'static' qualifier in
common.c.

Signed-off-by: Jason Cooper <jason@lakedaemon.net>