arm64: dts: allwinner: sun55i: Fix r-spi DMA

arm64: dts: allwinner: sun55i: Fix r-spi DMA

r-spi has DRQs for both the main and MCU DMA controllers on the A523 SoC
family, however it seems it that it is mainly routed to the MCU DMA
controller, with no obvious way to change it.

Change the DMA channels of r-spi to the MCU so that it works properly.

Fixes: 1bec3bd1f839 ("arm64: dts: allwinner: sun55i: Add SPI controllers")
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://patch.msgid.link/20260323171927.1256507-1-wens@kernel.org
Signed-off-by: Chen-Yu Tsai <wens@kernel.org>