Add Silent Mode boot controls

Add "reboot,forcedsilent" and "reboot,forcednonsilent"

Bug: 134521909
Test: Manually with 'adb reboot forcedsilent'
Change-Id: Ib07d2b78e6263bc25b23e9973590e399eaf4d7ca
diff --git a/bootstat/bootstat.cpp b/bootstat/bootstat.cpp
index 5d6cee4..8979e9a 100644
--- a/bootstat/bootstat.cpp
+++ b/bootstat/bootstat.cpp
@@ -436,6 +436,8 @@
     {"reboot,userspace_failed,watchdog_fork", 188},
     {"reboot,userspace_failed,*", 189},
     {"reboot,mount_userdata_failed", 190},
+    {"reboot,forcedsilent", 191},
+    {"reboot,forcednonsilent", 192},
 };
 
 // Converts a string value representing the reason the system booted to an