regulator: Updates for v4.13

A quiet release for the regulator API, a series of fairly small fixes
plus one new feature and a few new drivers:

 - Support for regulators with different settling times for rising and
   falling voltage changes.
 - New drivers for Allwinner AXP803, HiSilicon HI6421V530 and TI
   LP87565.
Merge remote-tracking branches 'regulator/topic/settle', 'regulator/topic/tps65910' and 'regulator/topic/tps65917' into regulator-next