usb: xhci: move xhci.h to include usb

The xhci.h header file is currently located under drivers/usb/xhci
Move it to the include/usb folder to make it available to drivers that
are not under drivers/usb/xhci

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
diff --git a/drivers/usb/host/xhci-rcar.c b/drivers/usb/host/xhci-rcar.c
index f2e91ef..c4d8811 100644
--- a/drivers/usb/host/xhci-rcar.c
+++ b/drivers/usb/host/xhci-rcar.c
@@ -12,7 +12,7 @@
 #include <usb.h>
 #include <wait_bit.h>
 
-#include "xhci.h"
+#include <usb/xhci.h>
 #include "xhci-rcar-r8a779x_usb3_v3.h"
 
 /* Register Offset */