ARM: dts: STiH410: set DWC3 dual role mode to peripheral

On STi 96boards, configure by default the micro USB connector
(managed by DWC3 hardware block) in peripheral mode.
This will allow to use fastboot feature.

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>