dmaengine: ti: deprecate '#dma-channels'

The generic property, used in most of the drivers and defined in generic
dma-common DT bindings, is 'dma-channels'.  Switch to new property while
keeping backward compatibility.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20220427161126.647073-4-krzysztof.kozlowski@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>