RD-E1-Edge platform consists of two clusters with eight CPUs each and
two processing elements (PE) per CPU. Commit a9fbf13e049e (plat/arm/sgi:
move topology information to board folder) defined the RD-E1-Edge
topology tree to have two clusters with eight CPUs each but PE per CPU
entries were not added. This patch fixes the topology tree accordingly.

Change-Id: I7f97f0013be60e5d51c214fce3962e246bae8a0b
Signed-off-by: Vijayenthiran Subramaniam <vijayenthiran.subramaniam@arm.com>