regulator: Updates for v4.4 This is quite a quiet release in terms of volume of patches but it includes a couple of really nice core changes - the work Sascha has done in particular is something I've wanted to get done for a long time but just never got round to myself. Highlights include: - Support from Sascha Hauer for setting the voltage of parent supplies based on requests from their children. This is used both to allow set_voltage() to work through a dumb switch and to improve the efficiency of systems where DCDCs are used to supply LDOs by minimising the voltage drop over the LDOs. - Removal of regulator_list by Tomeu Vizoso, meaning we're not duplicating the device list maintained by the driver core. - Support for Wolfson/Cirrus WM8998 and WM1818.