recovery: Blank screen during shutdown and reboot

Some hardware doesn't like having the panel on and still
active during power cycles, so just turn it off.

(based on Ied1f0802f5a2d45980ee33abf2456a291ba64beb)

Change-Id: Ied6bbc3a32fd1c7cf6ea3ec1b2bee298520651c3
diff --git a/recovery_main.cpp b/recovery_main.cpp
index de8ac1f..61b6de2 100644
--- a/recovery_main.cpp
+++ b/recovery_main.cpp
@@ -469,6 +469,7 @@
         continue;
       }
     }
+    ui->Stop();
     switch (ret) {
       case Device::SHUTDOWN:
         ui->Print("Shutting down...\n");