arm64: dts: amlogic: misc DT schema fixups

Take a pass at cleaning up a bunch of warnings
from 'make dtbs_check' that have crept in.

Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210421204833.18523-1-khilman@baylibre.com

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Signed-off-by: Arnd Bergmann <arnd@arndb.de>