Name
usb_interface_claimed — 
     returns true iff an interface is claimed
 
Arguments
- iface
- 
     the interface being checked
     
Return
   true (nonzero) iff the interface is claimed, else false
   (zero).
Note
   Callers must own the driver model's usb bus readlock.  So driver
   probe entries don't need extra locking, but other call contexts
   may need to explicitly claim that lock.