dt-bindings: arm: cpus: Add apple,avalanche & blizzard compatibles

These are the CPU cores in the Apple silicon M2 SoC.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Janne Grunau <j@jannau.net>
Signed-off-by: Hector Martin <marcan@marcan.st>