omni: Declare soong namespace for the generated_kernel_includes

Change-Id: I200d87526bc544f9d6265d588a42d786344d19c6
diff --git a/build/soong/Android.bp b/build/soong/Android.bp
index 761e186..389c8a1 100644
--- a/build/soong/Android.bp
+++ b/build/soong/Android.bp
@@ -1,4 +1,6 @@
 // Omni soong configs
+soong_namespace {
+}
 
 bootstrap_go_package {
     name: "soong-omnirom-generator",