dt-bindings: interconnect: qcom: Split out rpmh-common bindings

In preparation for the platforms, split out common definitions used in
rpmh-based interconnects.

Signed-off-by: Luca Weiss <luca.weiss@fairphone.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220525144404.200390-3-luca.weiss@fairphone.com


Signed-off-by: Georgi Djakov <djakov@kernel.org>