HID: hiddev.h: Fix example code.

Fix hiddev.h example code.
To get the correct usage code, you need to set report_type and
report_id.

Signed-off-by: Antonio Ospite <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

include/linux/hiddev.h

···
  * 		finfo.field_index = i;
  * 		ioctl(fd, HIDIOCGFIELDINFO, &finfo);
  * 		for (j = 0; j < finfo.maxusage; j++) {
+ * 			uref.report_type = rinfo.report_type;
+ * 			uref.report_id = rinfo.report_id;
  * 			uref.field_index = i;
  * 			uref.usage_index = j;
  * 			ioctl(fd, HIDIOCGUCODE, &uref);