USB: move <linux/usb_gadget.h> to <linux/usb/gadget.h>

Move <linux/usb_gadget.h> to <linux/usb/gadget.h>, reducing
some of the clutter in the main include directory.

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

diff --git a/drivers/usb/gadget/dummy_hcd.c b/drivers/usb/gadget/dummy_hcd.c
index 6479a36..9db2482 100644
--- a/drivers/usb/gadget/dummy_hcd.c
+++ b/drivers/usb/gadget/dummy_hcd.c
@@ -46,7 +46,7 @@
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
 #include <linux/usb.h>
-#include <linux/usb_gadget.h>
+#include <linux/usb/gadget.h>
 
 #include <asm/byteorder.h>
 #include <asm/io.h>