dt-bindings: interrupt-controller: loongarch: Fix mismatched compatible

The "compatible" doesn't match what the kernel is using. Fix it as
kernel using.

Fixes: 6b2748ad

 ("dt-bindings: interrupt-controller: add yaml for LoongArch CPU interrupt controller")
Reported-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/all/20221208020954.GA3368836-robh@kernel.org/
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Liu Peibao <liupeibao@loongson.cn>
Link: https://lore.kernel.org/r/20230401091304.12633-1-liupeibao@loongson.cn
[robh: Rename file to match compatible, fix subject typo]
Signed-off-by: Rob Herring <robh@kernel.org>