Convert the MXS DMA binding to DT schema format using json-schema.

Drop "interrupt-names" property, since it is broken. The drivers/dma/mxs-dma.c
in Linux kernel does not use it, the property contains duplicate array entries
in existing DTs, and even malformed entries (gmpi, should have been gpmi). Get
rid of that optional property altogether.

Update example node names to be standard dma-controller@ ,
add global interrupt-parent property into example.
Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20221219093713.328776-1-marex@denx.deSigned-off-by: Vinod Koul <vkoul@kernel.org>