usb: musb: mediatek: add support for vbus-supply regulator

Add the ability to control a regulator for VBUS. The regulator
will be enabled only when we are in host mode.

Signed-off-by: Fabien Parent <fparent@baylibre.com>
Change-Id: Ief542dd0b95fcab572a422315d13d5ef391de062
1 file changed