bugfix: change /dev/null to 666.

1）通过ueventd配置文件配置/dev/null权限为666
Signed-off-by: Nhandyohos <zhangxiaotian@huawei.com>
Change-Id: I116b31aa8b3f016c0ef91fb15955a24bd4c2f222

ueventd/etc/ueventd.config

@@ -13,6 +13,7 @@
 
 [device]
 # <device name> <mode> <uid> <gid> <parameter>
+/dev/null 0666 0 0
 /dev/binder 0666 0 0
 /dev/hwbinder 0666 0 0
 /dev/vndbinder 0666 0 0