usb: dwc2: detect device speed correctly

This doesn't make my LS keyboard work any better, but it does at least
report the correct speed in "usb tree".

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
diff --git a/drivers/usb/host/dwc2.c b/drivers/usb/host/dwc2.c
index 8f7c269..b506ff2 100644
--- a/drivers/usb/host/dwc2.c
+++ b/drivers/usb/host/dwc2.c
@@ -463,7 +463,11 @@
 		if (hprt0 & DWC2_HPRT0_PRTPWR)
 			port_status |= USB_PORT_STAT_POWER;
 
-		port_status |= USB_PORT_STAT_HIGH_SPEED;
+		if ((hprt0 & DWC2_HPRT0_PRTSPD_MASK) == DWC2_HPRT0_PRTSPD_LOW)
+			port_status |= USB_PORT_STAT_LOW_SPEED;
+		else if ((hprt0 & DWC2_HPRT0_PRTSPD_MASK) ==
+			 DWC2_HPRT0_PRTSPD_HIGH)
+			port_status |= USB_PORT_STAT_HIGH_SPEED;
 
 		if (hprt0 & DWC2_HPRT0_PRTENCHNG)
 			port_change |= USB_PORT_STAT_C_ENABLE;