usb: xhci: zynqmp: Remove support for !DM_USB

Switch to DM_USB was done and there is no need to keep !DM_USB code in
tree.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
index 3455e81..b4dd005 100644
--- a/drivers/usb/host/Kconfig
+++ b/drivers/usb/host/Kconfig
@@ -75,6 +75,7 @@
 config USB_XHCI_ZYNQMP
 	bool "Support for Xilinx ZynqMP on-chip xHCI USB controller"
 	depends on ARCH_ZYNQMP
+	depends on DM_USB
 	help
 	  Enables support for the on-chip xHCI controller on Xilinx ZynqMP SoCs.