The ASIC PCI bridge chipset from Motorola is named 'Raven'.
This chipset is used in the PowerPC Reference Platform (PReP),
but not restricted to it. Rename it accordingly.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Message-Id: <20210417103028.601124-5-f4bug@amsat.org>