usb: xhci: remove unused member 'parent' in xhci_regset struct

The member @parent of xhci_regset struct is not used in fact,
so remove it
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-debugfs.h

@@ -80,7 +80,6 @@ struct xhci_regset {
 	char			name[DEBUGFS_NAMELEN];
 	struct debugfs_regset32	regset;
 	size_t			nregs;
-	struct dentry		*parent;
 	struct list_head	list;
 };