Allow ssr_setup to read sysfs_data nodes

persist.sys.ssr.restart_level property is not taking
effect as ssr_setup is getting avc denials while accessing
/sys/bus/msm_subsys/* path.
Allow ssr_setup to read sysfs_data nodes.

Change-Id: Id61f01aeea993ec2e7c5dcd9cfd41abf9ac3f339