Don't hardcode the super partition name.

Bug: 116608795
Test: update_engine_unittests --gtest_filter=*BootControlAndroid*
Change-Id: Ibf5b0596278d280c7c47b110e7ba96bc04b28472
diff --git a/boot_control_android_unittest.cc b/boot_control_android_unittest.cc
index ea5e808..3e01be2 100644
--- a/boot_control_android_unittest.cc
+++ b/boot_control_android_unittest.cc
@@ -19,6 +19,7 @@
 #include <set>
 
 #include <android-base/strings.h>
+#include <fs_mgr.h>
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
@@ -78,7 +79,7 @@
   return kFakeDevicePath + name;
 }
 inline std::string GetSuperDevice() {
-  return GetDevice(LP_METADATA_PARTITION_NAME);
+  return GetDevice(fs_mgr_get_super_partition_name());
 }
 
 struct TestParam {