dt-bindings: arm: amlogic: Document the MNT Reform 2 CM4 adapter with a BPI-CM4 Module

The MNT Reform 2 CM4 adapter can be populated with any Raspberry Pi CM4
compatible module such as a BPI-CM4 Module, document that.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20240403-amlogic-v6-4-upstream-dsi-ccf-vim3-v12-1-99ecdfdc87fc@linaro.org


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