[PATCH] USB: fix for HID field index

The problem I'm having is that the field index is always returned as 0
when reading struct hiddev_usage_ref and I need something to
distinguish the input data as the usage code is the same.  I looked
through hid-core.c and hiddev.c and hiddev_hid_event is the only place
I could see field->index being used.  It wasn't being initialized
causing the input to always be returned as zero.
Signed-off-by: David Fries <dfries@mail.win.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/usb/input/hid-core.c

@@ -94,7 +94,8 @@ static struct hid_field *hid_register_field(struct hid_report *report, unsigned
 	memset(field, 0, sizeof(struct hid_field) + usages * sizeof(struct hid_usage)
 		+ values * sizeof(unsigned));
 
-	report->field[report->maxfield++] = field;
+	field->index = report->maxfield++;
+	report->field[field->index] = field;
 	field->usage = (struct hid_usage *)(field + 1);
 	field->value = (unsigned *)(field->usage + usages);
 	field->report = report;