hw/ppc/e500: Use SysBusDevice API to access TYPE_CCSR's internal resources

hw/ppc/e500: Use SysBusDevice API to access TYPE_CCSR's internal resources

Rather than accessing the attributes of TYPE_CCSR directly, use the SysBusDevice
API which exists exactly for that purpose. Furthermore, registering the memory
region with the SysBusDevice API makes it show up in QMP's `info qom-tree`
command.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Reviewed-by: BALATON Zoltan <balaton@eik.bme.hu>
[balaton: rebased]
Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Acked-by: Bernhard Beschow <shentey@gmail.com>
Message-ID: <619a58d1f83d2aad5b4feec930d46c64abff0977.1748012109.git.balaton@eik.bme.hu>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>