generated_kernel_headers: Also add usr/include/audio to include path

Needed for QGKI 5.4.

Change-Id: I44c77167828fdc3577cfd1eb548c8ceb7c418cbb
diff --git a/build/soong/Android.bp b/build/soong/Android.bp
index 93aab3d..d77f391 100644
--- a/build/soong/Android.bp
+++ b/build/soong/Android.bp
@@ -27,6 +27,7 @@
     export_include_dirs: [
         "usr/audio/include/uapi",
         "usr/include",
+        "usr/include/audio",
         "usr/include/audio/include/uapi",
         "usr/techpack/audio/include",
     ],