of: Add missing of_address.h to xilinx ehci driver

Build log:
In file included from drivers/usb/host/ehci-hcd.c:1208:
drivers/usb/host/ehci-xilinx-of.c: In function 'ehci_hcd_xilinx_of_probe':
drivers/usb/host/ehci-xilinx-of.c:168: error: implicit declaration of function 'of_address_to_resource'
Signed-off-by: John Williams <john.williams@petalogix.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/usb/host/ehci-xilinx-of.c

@@ -29,6 +29,7 @@
 
 #include <linux/of.h>
 #include <linux/of_platform.h>
+#include <linux/of_address.h>
 
 /**
  * ehci_xilinx_of_setup - Initialize the device for ehci_reset()