loongarch: dts: remove non-existent DAC from 2k1000-ref

loongarch: dts: remove non-existent DAC from 2k1000-ref

The 2k1000 reference boards do not have a Rohm DAC on them as far as I
can tell, and they certainly do not have a dh2228fv, as this device does
not actually exist! Remove the dac nodes from the devicetrees as it is
not acceptable to pretend to have a device on a board in order to bind
the spidev driver in Linux.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240717-preacher-sandal-2aeffa322b9f@spud
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>