Specify no resource_dirs for SystemUI

The res directory is already included via the SystemUI-core
library. The default for resource_dirs is ["res"] if it exists,
so explicitly clear it to avoid depending on it twice.

Bug: 124035856
Test: m SystemUI
Change-Id: Ia1b06cd9eff4e614684efde34288cf9ebd895870
diff --git a/packages/SystemUI/Android.bp b/packages/SystemUI/Android.bp
index 5b3164e..7d0291f 100644
--- a/packages/SystemUI/Android.bp
+++ b/packages/SystemUI/Android.bp
@@ -78,6 +78,7 @@
     static_libs: [
         "SystemUI-core",
     ],
+    resource_dirs: [],
 
     platform_apis: true,
     product_specific: true,