dt-bindings: arm/cpus: Add missing Applied Micro CPU compatibles

"apm,potenza" and "apm,strega" CPU compatibles have been in use for some
time.

Link: https://lore.kernel.org/r/20250812181428.69490-1-robh@kernel.org


Signed-off-by: Rob Herring (Arm) <robh@kernel.org>