usb: dwc2: Add force-b-session-valid support

Handle "force-b-session-valid" property from DT.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
diff --git a/include/usb/dwc2_udc.h b/include/usb/dwc2_udc.h
index 4068de0..3cf20ea 100644
--- a/include/usb/dwc2_udc.h
+++ b/include/usb/dwc2_udc.h
@@ -22,6 +22,7 @@
 	unsigned int	rx_fifo_sz;
 	unsigned int	np_tx_fifo_sz;
 	unsigned int	tx_fifo_sz;
+	bool		force_b_session_valid;
 };
 
 int dwc2_udc_probe(struct dwc2_plat_otg_data *pdata);