dt-bindings: net: snps: remove duplicate name

commit ce8b3ad1 upstream.

snps,dwmac has duplicated name for loongson,ls2k-dwmac and
loongson,ls7a-dwmac.

Signed-off-by: Dongjin Yang <dj76.yang@samsung.com>
Fixes: 68277749 ("dt-bindings: dwmac: Add bindings for new Loongson SoC and bridge chip")
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220404022857epcms1p6e6af1a6a86569f339e50c318abde7d3c@epcms1p6


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>