Add bluetooth_prop to system_server sepolicy.

We need to be able to access Bluetooth sysprops from
BluetoothManagerService.

Bug: 217292806
Test: atest CtsBluetoothTestCases
Tag: #feature
Change-Id: Ia4d5d286ccf94f61bbc87e9063d22b8822806e5c
diff --git a/private/system_server.te b/private/system_server.te
index aedebaf..6186a32 100644
--- a/private/system_server.te
+++ b/private/system_server.te
@@ -693,6 +693,7 @@
 # Property Service write
 set_prop(system_server, system_prop)
 set_prop(system_server, bootanim_system_prop)
+set_prop(system_server, bluetooth_prop)
 set_prop(system_server, exported_system_prop)
 set_prop(system_server, exported3_system_prop)
 set_prop(system_server, safemode_prop)