Add support for Richtek RT6190 36V 4-wwtich regulator

Merge series from cy_huang <u0084500@gmail.com>:

The RT6190 is a 4-switch Buck-Boost controller designed for USB power delivery
(USB PD). It operates with wide input voltage range from 4.5V to 36V, and the
output voltage can be programmable between 3V and 36V. It implements peak
current mode control mechanism to deliver up to 100W power with the
programmable constant voltage and constant current output. It also has built-in
charge pumps for driving external low-cost N-MOSFETs to control the power path.