rockchip: select DM_USB for rockchip SoC

Select DM_USB to compatible with USB DM driver model.

Signed-off-by: MengDongyang <daniel.meng@rock-chips.com>
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a311215..9b85635 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -896,6 +896,7 @@
 	select DM_SERIAL
 	select DM_SPI
 	select DM_SPI_FLASH
+	select DM_USB if USB
 
 config TARGET_THUNDERX_88XX
 	bool "Support ThunderX 88xx"