dt-bindings: mfd: qcom,tcsr: Document SDX55 TCSR

Add compatible for SDX55 TCSR block.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230306072618.10770-1-krzysztof.kozlowski@linaro.org