usb: dwc2: Add delay to fix the USB detection problem on SoCFPGA

With patch c998da0d (usb: Change power-on / scanning timeout handling),
the USB scanning is started earlier and with a smaller timeout. This
resulted on SoCFPGA (using the DWC2 driver) in some USB sticks not
getting detected any more. This patch now adds a 1 second delay (in
the host mode only) to the DWC2 driver before the scanning is started.
With this delay, now all problematic USB keys are detected successfully
again. And there is no need any more to change the delay / timeout
in the common USB code (usb_hub.c).

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Chin Liang See <clsee@altera.com>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: Marek Vasut <marex@denx.de>

drivers/usb/host/dwc2.c

@@ -1088,6 +1088,15 @@ static int dwc2_init_common(struct dwc2_priv *priv)
 		}
 	}
 
+	/*
+	 * Add a 1 second delay here. This gives the host controller
+	 * a bit time before the comminucation with the USB devices
+	 * is started (the bus is scanned) and  fixes the USB detection
+	 * problems with some problematic USB keys.
+	 */
+	if (readl(&regs->gintsts) & DWC2_GINTSTS_CURMODE_HOST)
+		mdelay(1000);
+
 	return 0;
 }