dt-bindings: remoteproc: qcom,sc8180x-pas: split into separate file

Split SC8180x remote processor Peripheral Authentication Service bindings
into their own file to reduce complexity and make maintenance easier.

The binding is incomplete due to lack of upstreamed DTS - no example and
not all power domains defined.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20221124184333.133911-12-krzysztof.kozlowski@linaro.org