dt-bindings: dma: Drop undocumented examples

dt-bindings: dma: Drop undocumented examples

The compatibles "ti,omap-sdma" and "ti,dra7-dma-crossbar" aren't documented
by a schema which causes warnings:

Documentation/devicetree/bindings/dma/dma-controller.example.dtb: /example-0/dma-controller@48000000: failed to match any schema with compatible: ['ti,omap-sdma']
Documentation/devicetree/bindings/dma/dma-router.example.dtb: /example-0/dma-router@4a002b78: failed to match any schema with compatible: ['ti,dra7-dma-crossbar']

As no one has cared to fix them, just drop them.

Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20231122235050.2966280-1-robh@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>