MLK-18794-1 usb: host: xhci: add .bus_suspend override

Some platforms (eg: Cadence USB3) have special requirements to add
platform USB register setting between xhci_bus_suspend and
platform USB controller suspend routine. Eg, The Cadence USB3 needs
RX detect clock switch from 24Mhz to 32Khz within 100ms after set
port to U3, but sometimes, for USB3 HUB connection, the USB2
bus suspend will cost more than 100ms, and introduce the disconnection
before the PHY enters low power mode, then the state is in mess from
controller side.

So in this commit, we introduce .bus_suspend for xhci_driver_overrides
for above use cases.

Signed-off-by: Peter Chen <peter.chen@nxp.com>
(cherry picked from commit f6baa57)

drivers/usb/host/xhci.c

@@ -5372,6 +5372,8 @@ void xhci_init_driver(struct hc_driver *drv,
 			drv->reset = over->reset;
 		if (over->start)
 			drv->start = over->start;
+		if (over->bus_suspend)
+			drv->bus_suspend = over->bus_suspend;
 	}
 }
 EXPORT_SYMBOL_GPL(xhci_init_driver);

drivers/usb/host/xhci.h

@@ -1902,6 +1902,7 @@ struct xhci_driver_overrides {
 	size_t extra_priv_size;
 	int (*reset)(struct usb_hcd *hcd);
 	int (*start)(struct usb_hcd *hcd);
+	int (*bus_suspend)(struct usb_hcd *hcd);
 };
 
 #define	XHCI_CFC_DELAY		10