This commit imports the Linux v5.3 state of the driver. This allows us
to regulate at least the v3v3 voltage rail used by the DK1 and DK2
Ethernet PHY and SD-Card. Eventually, this driver should be used by the
USB host driver to supply the vbus voltage as well.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>