Add the specific compatible string for the DWC2 IP found in the STM32MP15
SoCs.
STM32MP15 SoCs uses sensing comparators to detect Vbus valid levels and
ID pin state. usb33d-supply described the regulator supplying Vbus and ID
sensing comparators.
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Rob Herring <robh@kernel.org>