regulator: Updates for v4.18 Quite a lot of core work this time around, though not 100% successful. We gained support for runtime mode changes thanks to David Collins and improved support for write only regulators (ones where we can't read back the configuration) from Douglas Anderson. There's been quite a bit of work from Linus Walleij on converting from specfying GPIOs by numbers to descriptors. Sadly the testing turned out to be less good than we had hoped and so a lot of this had to be reverted. We also have the start of updates to use coupled regulators from Maciej Purski, unfortunately there are further problems there so the last couple of patches have been reverted. We also have new drivers for BD71837 and SY8106A devices, SAW regulators on Qualcomm SPMI and dropped support for some preproduction chips that never made it to market from the AB8500 driver.