[POWERPC] 85xxCDS: MPC8548 DTS cleanup.

Added the P2P bridge present on the Arcadia base board and moved the VIA
Southbridge behind the bridge to reflect its actual position in the bus
organization. Added the RTC that's in the VIA Southbridge and expanded
the ranges array for the SOC node to allow proper address translation of
the RTC registers.

Signed-off-by: Randy Vinson <rvinson@mvista.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>