xhci: dbc: Add device pointer to dbc structure

Currently the dbc structure contains a pointer to struct xhci_hcd,
and dbc functions use that to dig up the underlying device pointer.

We are trying to decouple xhci and dbc code, and prepare for
code that use dbc such as dbctty into into real device drivers.
This is one step along the way.

Keep functionality the same and keep the xhci pointer, and
let the new device pointer point to the xhci device for now.
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200723144530.9992-8-mathias.nyman@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-dbgcap.c

@@ -878,6 +878,7 @@ static int xhci_do_dbc_init(struct xhci_hcd *xhci)
 	spin_unlock_irqrestore(&xhci->lock, flags);
 
 	dbc->xhci = xhci;
+	dbc->dev = xhci_to_hcd(xhci)->self.sysdev;
 	INIT_DELAYED_WORK(&dbc->event_work, xhci_dbc_handle_events);
 	spin_lock_init(&dbc->lock);
 

drivers/usb/host/xhci-dbgcap.h

@@ -133,6 +133,7 @@ struct dbc_port {
 
 struct xhci_dbc {
 	spinlock_t			lock;		/* device access */
+	struct device			*dev;
 	struct xhci_hcd			*xhci;
 	struct dbc_regs __iomem		*regs;
 	struct xhci_ring		*ring_evt;