arm: dts: axxia: the unit-address of cpu4 should match the reg value

The unit-address of cpu4 wasn't changed to match the reg value along
with other cpus. This patch is to fix this.

Reported-by: Mikael Beckius <mikael.beckius@windriver.com>
Signed-off-by: Quanyang Wang <quanyang.wang@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>