bluetooth: hogp: Fix bt_hogp_rep_unsubscribe issue

The bt_hogp_rep_unsubscribe did not reset the rep->notify_cb,
while bt_hogp_rep_subscribe returned an error if
notify_cb was not null. Thus, it would be impossible
to subscribe again to the report notification after
unsubscribing.

This commit fixes this.

Signed-off-by: Artur Hadasz <artur.hadasz@nordicsemi.no>

Author: ahasztag

subsys/bluetooth/services/hogp.c

@@ -1031,9 +1031,13 @@ static uint8_t rep_notify_process(struct bt_conn *conn,
 	 */
 	if (data != NULL) {
 		rep->size = (uint8_t)length;
+		return rep->notify_cb(rep->hogp, rep, 0, data);
 	}
 
-	return rep->notify_cb(rep->hogp, rep, 0, data);
+
+	rep->notify_cb = NULL;
+
+	return BT_GATT_ITER_CONTINUE;
 }
 
 int bt_hogp_rep_subscribe(struct bt_hogp *hogp,