USB: EHCI: fix build error in ChipIdea host driver

This patch (as1629) fixes a build error in the ChipIdea host driver
when compiled for the ARM architecture.  The error was introduced
by commit 99f91934 (USB: EHCI: make
ehci-platform a separate driver).

The fix is simple; an additional header-file #include is needed.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Tested-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/chipidea/host.c

@@ -20,6 +20,7 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/io.h>
 #include <linux/usb.h>
 #include <linux/usb/hcd.h>
 #include <linux/usb/chipidea.h>