arm64: dts: freescale: imx8mp-venice-gw73xx-2x: fix USB vbus regulator

When using usb-conn-gpio to control USB role and VBUS, the vbus-supply
property must be present in the usb-conn-gpio node. Additionally it
should not be present in the phy node as that isn't what controls vbus
and will upset the use count.

This resolves an issue where VBUS is enabled with OTG in peripheral
mode.

Fixes: ad9a12f7 ("arm64: dts: imx8mp-venice: Fix USB connector description")
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>