Move sysfs_thermal to global policy and grant access.

sysfs_thermal nodes are common enough to warrant an entry in global
policy and the new HardwarePropertiesManagerService exists explicitly to
expose some of this information.

Address the following denials:
avc: denied { search } for name="thermal" dev="sysfs" ino=17509 scontext=u:r:system_server:s0 tcontext=u:object_r:sysfs_thermal:s0 tclass=dir permissive=1
avc: denied { read } for name="temp" dev="sysfs" ino=17848 scontext=u:r:system_server:s0 tcontext=u:object_r:sysfs_thermal:s0 tclass=file permissive=1
avc: denied { open } for path="/sys/devices/virtual/thermal/thermal_zone8/temp" dev="sysfs" ino=17848 scontext=u:r:system_server:s0 tcontext=u:object_r:sysfs_thermal:s0 tclass=file permissive=1
avc: denied { getattr } for path="/sys/devices/virtual/thermal/thermal_zone8/temp" dev="sysfs" ino=17848 scontext=u:r:system_server:s0 tcontext=u:object_r:sysfs_thermal:s0 tclass=file permissive=1

Bug: 27809332
Change-Id: I2dbc737971bf37d197adf0d5ff07cb611199300d

file.te

@@ -34,6 +34,9 @@ type configfs, fs_type;
 type sysfs_devices_system_cpu, fs_type, sysfs_type;
 # /sys/module/lowmemorykiller
 type sysfs_lowmemorykiller, fs_type, sysfs_type;
+
+type sysfs_thermal, sysfs_type, fs_type;
+
 type sysfs_zram, fs_type, sysfs_type;
 type sysfs_zram_uevent, fs_type, sysfs_type;
 type inotify, fs_type, mlstrustedobject;

system_server.te

@@ -170,6 +170,8 @@ allow system_server sysfs:file rw_file_perms;
 allow system_server sysfs_nfc_power_writable:file rw_file_perms;
 allow system_server sysfs_devices_system_cpu:file w_file_perms;
 allow system_server sysfs_mac_address:file r_file_perms;
+allow system_server sysfs_thermal:dir search;
+allow system_server sysfs_thermal:file r_file_perms;
 
 # Access devices.
 allow system_server device:dir r_dir_perms;