usb: dwc2: stm32mp15: set otg_rev

STM32MP15 complies with the OTG 2.0. Set OTG revision accordingly. It is
useful for the of_usb_update_otg_caps() routine to check and update
otg_rev to the lower value between DT and provided params.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/1634133425-25670-5-git-send-email-fabrice.gasnier@foss.st.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>