ARM: Kirkwood: Support basic hotplug for PCI-E

Unconditionally register the PCI-E bus, even if the link is currently
down. When the link is brought up the bus can be scanned through
/sys/bus/pci/rescan or otherwise. Since the HW has no interrupt for
link up, userspace will have to take care of the timing.

An earlier version of this was contingent on CONFIG_HOTPLUG, but
that is being removed from the kernel.

This also fixes printing the link up/down message to be displayed
on one line (structured logging broke this?)

Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>