usb: phy: generic: Get the vbus supply

usb: phy: generic: Get the vbus supply

[ Upstream commit 75fd6485cccef269ac9eb3b71cf56753341195ef ]

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: 7acc9973e3c4 ("usb: phy: generic: add vbus support")
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Link: https://lore.kernel.org/r/20240123225111.1629405-3-sean.anderson@seco.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>