xhci: Avoid global symbol pollution with handshake.

Non-static xHCI driver symbols should start with the "xhci_" prefix, in
order to avoid namespace pollution.  Rename the "handshake" function to
"xhci_handshake".

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Reported-by: Ben Hutchings <ben@decadent.org.uk>

drivers/usb/host/xhci.h

@@ -1720,7 +1720,7 @@ static inline void xhci_unregister_plat(void)
 
 /* xHCI host controller glue */
 typedef void (*xhci_get_quirks_t)(struct device *, struct xhci_hcd *);
-int handshake(struct xhci_hcd *xhci, void __iomem *ptr,
+int xhci_handshake(struct xhci_hcd *xhci, void __iomem *ptr,
 		u32 mask, u32 done, int usec);
 void xhci_quiesce(struct xhci_hcd *xhci);
 int xhci_halt(struct xhci_hcd *xhci);