dt-bindings: arm: amazon: add missing alpine-v2 DT binding

Amazon Annapurna Labs Alpine family includes: Alpine-v1, Alpine-v2.

This patch adds the missing DT binding of Alpine-v2 in amazon,al.yaml.

Link: https://lore.kernel.org/r/20200724132654.16549-5-hhhawa@amazon.com


Signed-off-by: Hanna Hawa <hhhawa@amazon.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Antoine Tenart <antoine.tenart@bootlin.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>