usb: dwc2: add support for STM32MP1

Add compatible "st,stm32mp1-hsotg" and associated driver data to manage
the usb33d-supply and the ST specific register for VBus sensing.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
# Conflicts:
#	drivers/usb/gadget/dwc2_udc_otg.c
Reviewed-by: Lukasz Majewski <lukma@denx.de>
diff --git a/doc/device-tree-bindings/usb/dwc2.txt b/doc/device-tree-bindings/usb/dwc2.txt
index 6dc3c4a..eb60ffa 100644
--- a/doc/device-tree-bindings/usb/dwc2.txt
+++ b/doc/device-tree-bindings/usb/dwc2.txt
@@ -37,6 +37,8 @@
 - g-rx-fifo-size: size of rx fifo size in gadget mode.
 - g-np-tx-fifo-size: size of non-periodic tx fifo size in gadget mode.
 - g-tx-fifo-size: size of periodic tx fifo per endpoint (except ep0) in gadget mode.
+- usb33d-supply: external VBUS and ID sensing comparators supply, in order to
+  perform OTG operation, used on STM32MP1 SoCs.
 
 Deprecated properties:
 - g-use-dma: gadget DMA mode is automatically detected