usb: lowlevel interface change to support multiple controllers

Carry an index in the lowlevel usb functions to make specify the
respective usb controller.

Also pass through an controller struct from lowlevel_init to the
creation of the root usb device of this controller.

Signed-off-by: Lucas Stach <dev@lynxeye.de>
Reviewed-by: Marek Vasut <marex@denx.de>
diff --git a/arch/powerpc/cpu/ppc4xx/usb_ohci.c b/arch/powerpc/cpu/ppc4xx/usb_ohci.c
index 14c6a28..4ce2726 100644
--- a/arch/powerpc/cpu/ppc4xx/usb_ohci.c
+++ b/arch/powerpc/cpu/ppc4xx/usb_ohci.c
@@ -1566,7 +1566,7 @@
  */
 static char ohci_inited = 0;
 
-int usb_lowlevel_init(void)
+int usb_lowlevel_init(int index, void **controller)
 {
 	memset (&gohci, 0, sizeof (ohci_t));
 	memset (&urb_priv, 0, sizeof (urb_priv_t));
@@ -1624,7 +1624,7 @@
 	return 0;
 }
 
-int usb_lowlevel_stop(void)
+int usb_lowlevel_stop(int index)
 {
 	/* this gets called really early - before the controller has */
 	/* even been initialized! */