xhci: dbc: Get the device pointer from dbc structure in dbc_ep_do_queue()

dbc_ep_do_queue() can now get the device pointer directly from dbc
structure instead of going through the xhci_hcd structure.

No functional changes
This change helps decoupling xhci and DbC
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200723144530.9992-12-mathias.nyman@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-dbgcap.c

@@ -267,11 +267,8 @@ static int
 dbc_ep_do_queue(struct dbc_ep *dep, struct dbc_request *req)
 {
 	int			ret;
-	struct device		*dev;
 	struct xhci_dbc		*dbc = dep->dbc;
-	struct xhci_hcd		*xhci = dbc->xhci;
-
-	dev = xhci_to_hcd(xhci)->self.sysdev;
+	struct device		*dev = dbc->dev;
 
 	if (!req->length || !req->buf)
 		return -EINVAL;