usb: dwc3-of-simple: Add support for RK3399

Add compatible string for RK3399 and enable it by default on
Rockchip platforms with USB3 support.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
index b1188bc..ac68aa2 100644
--- a/drivers/usb/host/Kconfig
+++ b/drivers/usb/host/Kconfig
@@ -24,6 +24,7 @@
 config USB_XHCI_DWC3_OF_SIMPLE
 	bool "DesignWare USB3 DRD Generic OF Simple Glue Layer"
 	depends on DM_USB
+	default y if ARCH_ROCKCHIP
 	default y if DRA7XX
 	help
 	  Support USB2/3 functionality in simple SoC integrations with