Fix Brillo build.

boot_control_ should have been boot_control.

Bug: None
Test: `make dist` on Brillo.
Change-Id: I5672dd029d20b62ab27450da2f792b50d9364532
diff --git a/update_attempter.cc b/update_attempter.cc
index 4e300d7..d36f7fd 100644
--- a/update_attempter.cc
+++ b/update_attempter.cc
@@ -1143,7 +1143,7 @@
       // Mark the current slot as successful again, since marking it as active
       // may reset the successful bit. We ignore the result of whether marking
       // the current slot as successful worked.
-      if (!boot_control_->MarkBootSuccessfulAsync(Bind([](bool successful){})))
+      if (!boot_control->MarkBootSuccessfulAsync(Bind([](bool successful){})))
         ret_value = false;
 
       // Notify the PayloadState that the successful payload was canceled.