powerpc/amigaone: Generic device tree for all AmigaOne boards

This device tree does not provide the correct CPU name, as various CPU
models and revisions are used in AmigaOnes. Also the PCI root node does
not contain a interrupt mapping property, as all boards have different
interrupt routing. However the kernel can do a 1:1 mapping of all PCI
interrupts, as only i8259 legacy interrupts are used.

Signed-off-by: Gerhard Pircher <gerhard_pircher@gmx.net>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>