usb: dwc2: don't use ID/Vbus detection if usb-role-switch on STM32MP15 SoCs

If usb-role-switch is present in the device tree, it means that ID and Vbus
signals are not connected to the OTG controller but to an external
component (GPIOs, Type-C controller). In this configuration, usb role
switch is used to force valid sessions on STM32MP15 SoCs.

Acked-by: Minas Harutyunyan <hminas@synopsys.com>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>