Change name of overlay subdir 'sku'->'theme'

The name 'sku' does not fit well as we recommend to use the same
value for different SKUs if vendors wish to have the same colors
on those SKUs.

Bug: 32268656
Change-Id: Ib5e5a3386676453dafeb13a6a6bf91f81bb48a11
diff --git a/libs/androidfw/AssetManager.cpp b/libs/androidfw/AssetManager.cpp
index 4c1c1b9..98168ef 100644
--- a/libs/androidfw/AssetManager.cpp
+++ b/libs/androidfw/AssetManager.cpp
@@ -79,7 +79,7 @@
 const char* AssetManager::RESOURCES_FILENAME = "resources.arsc";
 const char* AssetManager::IDMAP_BIN = "/system/bin/idmap";
 const char* AssetManager::OVERLAY_DIR = "/vendor/overlay";
-const char* AssetManager::OVERLAY_SKU_DIR_PROPERTY = "ro.boot.vendor.overlay.sku";
+const char* AssetManager::OVERLAY_THEME_DIR_PROPERTY = "ro.boot.vendor.overlay.theme";
 const char* AssetManager::TARGET_PACKAGE_NAME = "android";
 const char* AssetManager::TARGET_APK_PATH = "/system/framework/framework-res.apk";
 const char* AssetManager::IDMAP_DIR = "/data/resource-cache";