dt-bindings: Drop Jee Heng Sia

Emails to Jee Heng Sia bounce ("550 #5.1.0 Address rejected.").  Add
Keembay platform maintainers as Keembay I2S maintainers.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20221205164254.36418-1-krzysztof.kozlowski@linaro.org


Signed-off-by: Rob Herring <robh@kernel.org>