usb: dwc3: Add dwc3 glue driver support for STi

This patch adds the ST glue logic to manage the DWC3 HC
on STiH407 SoC family. It configures the internal glue
logic and syscfg registers.

Part of this code been extracted from kernel.org driver
(drivers/usb/dwc3/dwc3-st.c)

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/usb/host/Makefile b/drivers/usb/host/Makefile
index ab5a99f..29afb7c 100644
--- a/drivers/usb/host/Makefile
+++ b/drivers/usb/host/Makefile
@@ -60,6 +60,7 @@
 obj-$(CONFIG_USB_XHCI_MVEBU) += xhci-mvebu.o
 obj-$(CONFIG_USB_XHCI_OMAP) += xhci-omap.o
 obj-$(CONFIG_USB_XHCI_PCI) += xhci-pci.o
+obj-$(CONFIG_USB_XHCI_STI) += dwc3-sti-glue.o
 
 # designware
 obj-$(CONFIG_USB_DWC2) += dwc2.o