ARM: dts: stm32: update vbus-supply of usbphyc_port0 on stm32mp157c-ev1

phy-stm32-usbphyc bindings uses a connector node with vbus-supply
property.

Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>