interconnect: Add generic interconnect driver for Exynos SoCs
This patch adds a generic interconnect driver for Exynos SoCs in order to provide interconnect functionality for each "samsung,exynos-bus" compatible device. The SoC topology is a graph (or more specifically, a tree) and its edges are described by specifying in the 'interconnects' property the interconnect consumer path for each interconnect provider DT node. Each bus is now an interconnect provider and an interconnect node as well (cf. Documentation/interconnect/interconnect.rst), i.e. every bus registers itself as a node. Node IDs are not hard coded but rather assigned dynamically at runtime. This approach allows for using this driver with various Exynos SoCs. Frequencies requested via the interconnect API for a given node are propagated to devfreq using dev_pm_qos_update_request(). Please note that it is not an error when CONFIG_INTERCONNECT is 'n', in which case all interconnect API functions are no-op. The samsung,data-clk-ratio DT property is used to specify the ratio of the interconect bandwidth to the minimum data clock frequency for each bus. Due to unspecified relative probing order, -EPROBE_DEFER may be propagated to ensure that the parent is probed before its children. Reviewed-by:Chanwoo Choi <cw00.choi@samsung.com> Tested-by: