dt-bindings: Fix typo in comment

Fix typo in the comment

Signed-off-by: Slark Xiao <slark_xiao@163.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220721011746.19663-1-slark_xiao@163.com