USB: <linux/usb_ch9.h> becomes <linux/usb/ch9.h>

This moves <linux/usb_ch9.h> to <linux/usb/ch9.h> to reduce some of the
clutter of usb header files.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/gadget/usbstring.c b/drivers/usb/gadget/usbstring.c
index b173576..3459ea6 100644
--- a/drivers/usb/gadget/usbstring.c
+++ b/drivers/usb/gadget/usbstring.c
@@ -14,7 +14,7 @@
 #include <linux/device.h>
 #include <linux/init.h>
 
-#include <linux/usb_ch9.h>
+#include <linux/usb/ch9.h>
 #include <linux/usb_gadget.h>
 
 #include <asm/unaligned.h>