usb: properly re-initialize the USB keyboard.

Allow to reconfigure properly the USB keyboard driver when we enumerate
several times the USB devices and its position in the device tree has
changes.

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
Tested-by: Vincent Palatin <vpalatin@chromium.org>

common/usb_kbd.c

@@ -496,6 +496,7 @@ int drv_usb_kbd_init(void)
 		if (old_dev) {
 			/* Already registered, just return ok. */
 			debug("USB KBD: is already registered.\n");
+			usb_kbd_deregister();
 			return 1;
 		}