arm64: dts: amazon: rename al folder to be amazon

As preparation to add device tree binding for Amazon's Annapurna Labs
Alpine v3 support. Rename al device tree folder to be amazon.

Link: https://lore.kernel.org/r/20200724132654.16549-3-hhhawa@amazon.com


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