dt-bindings: dma: allwinner,sun50i-a64-dma: Fix min/max typo

The conditional block for variants with a second clock should have set
minItems, not maxItems, which was already 2. Since clock-names requires
two items, this typo should not have caused any problems.

Fixes: edd14218

 ("dt-bindings: dmaengine: Convert Allwinner A31 and A64 DMA to a schema")
Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220702031903.21703-1-samuel@sholland.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>