Allow apps to read ro.init.userspace_reboot.is_supported

This property essentially implements
PowerManager.isRebootingUserspaceSupported[0] public API, hence apps
should be able to read it.

[0]: https://cs.android.com/android/_/android/platform/frameworks/base/+/73cab34d9f49013f4ede893aa00802b937d0d5a9:core/java/android/os/PowerManager.java;l=1397

Test: m checkbuild
Test: atest CtsUserspaceRebootHostSideTestCases
Test: adb shell getprop ro.init.userspace_reboot.is_supported
Bug: 135984674
Change-Id: I09cab09735760529de81eb6d5306f052ee408a6e
diff --git a/private/domain.te b/private/domain.te
index 907d1b8..08d963c 100644
--- a/private/domain.te
+++ b/private/domain.te
@@ -77,6 +77,7 @@
     get_prop({coredomain appdomain shell}, exported3_radio_prop)
     get_prop({coredomain appdomain shell}, exported3_system_prop)
     get_prop({coredomain appdomain shell}, exported_camera_prop)
+    get_prop({coredomain appdomain shell}, userspace_reboot_config_prop)
     get_prop({coredomain shell}, userspace_reboot_exported_prop)
     get_prop({coredomain shell}, userspace_reboot_prop)
     get_prop({domain -coredomain -appdomain}, vendor_default_prop)