usb: phy: generic: Get the vbus supply

usb: phy: generic: Get the vbus supply

While support for working with a vbus was added, the regulator was never
actually gotten (despite what was documented). Fix this by actually
getting the supply from the device tree.

Fixes: e79a1a456580 ("usb: phy: generic: add vbus support")
Cc: stable <stable@kernel.org>
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Link: https://lore.kernel.org/r/20220425171412.1188485-3-sean.anderson@seco.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>