dt-bindings: arm: amlogic: Document the boards with the BPI-CM4 connected

The BPI-CM4 module with an Amlogic A311D SoC is a module compatible
with the Raspberry Pi CM4 specifications.

Document the boards using this module, by specifying the BananaPi CM4
compatible in addition to the baseboard compatible.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/20230303-topic-amlogic-upstream-bpi-cm4-v2-1-2ecfde76fc4d@linaro.org


Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>