Add ESP32-S31 USB DWC/UTMI LL headers, SoC register structures, peripheral
descriptors, capabilities, and linker mappings so the HS OTG controller and
UTMI PHY can be built in esp_hal_usb.
Introduce SOC_USB_FSLS_PHY_NUM on USB-OTG targets to separate FSLS USB_WRAP
support from OTG/UTMI support. Use it to gate usb_wrap, the USB PHY driver,
docs, and example build rules on targets without an FSLS PHY.
Also add UTMI data pulldown control to the HAL, clear the boot-time DWC
suspend state on ESP32-S31, alias the legacy internal PHY target to UTMI for
backward compatibility, and extend usb_phy tests for UTMI-only targets.
igor.masar
Tomas Rezucha