device_find_child — device iterator for locating a particular device.
| struct device * device_find_child ( | struct device * parent, | 
| void * data, | |
| int (*match) (struct device *dev, void *data)); | 
parentparent struct device
dataData to pass to match function
matchCallback function to check device
   This is similar to the device_for_each_child function above, but it
   returns a reference to a device that is 'found' for later use, as
   determined by the match callback.
   
The callback should return 0 if the device doesn't match and non-zero if it does. If the callback returns non-zero and a reference to the current device can be obtained, this function will return to the caller and not iterate over any more devices.