Making sys.boot.reason.last restricted

sys.boot.reason.last needs to be readable by SysUI to correctly display the reason why authentication is required to unlock the phone.

Bug: 299327097
Test: presubmit
Change-Id: I9f83ade92858056609bc665ecb6ce9b93eb051e4
diff --git a/private/platform_app.te b/private/platform_app.te
index 1bd0020..cd95353 100644
--- a/private/platform_app.te
+++ b/private/platform_app.te
@@ -116,6 +116,9 @@
 # allow platform apps to read qemu.hw.mainkeys
 get_prop(platform_app, qemu_hw_prop)
 
+# allow platform apps to read sys.boot.reason.last
+get_prop(platform_app, last_boot_reason_prop)
+
 # allow platform apps to create symbolic link
 allow platform_app app_data_file:lnk_file create_file_perms;