USB: make hcd.h public (drivers dependency)

The usbcore headers: hcd.h and hub.h are shared between usbcore,
HCDs and a couple of other drivers (e.g. USBIP modules).
So, it makes sense to move them into a more public location and
to cleanup dependency of those modules on kernel internal headers.
This patch moves hcd.h from drivers/usb/core into include/linux/usb/

Signed-of-by: Eric Lescouet <eric@lescouet.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
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 5e09664..4f9e578 100644
--- a/drivers/usb/gadget/dummy_hcd.c
+++ b/drivers/usb/gadget/dummy_hcd.c
@@ -47,6 +47,7 @@
 #include <linux/platform_device.h>
 #include <linux/usb.h>
 #include <linux/usb/gadget.h>
+#include <linux/usb/hcd.h>
 
 #include <asm/byteorder.h>
 #include <asm/io.h>
@@ -55,9 +56,6 @@
 #include <asm/unaligned.h>
 
 
-#include "../core/hcd.h"
-
-
 #define DRIVER_DESC	"USB Host+Gadget Emulator"
 #define DRIVER_VERSION	"02 May 2005"