Update linkerconfig configuration format

Update linkerconfig configuration format as json.

Bug: 169634881
Test: cuttelfish boot succeeded
Change-Id: I297ffc9e5c8d8916b2e7e0b3e837b6b82247401b
diff --git a/apex/Android.bp b/apex/Android.bp
index c6c4cbf..5bf078a 100644
--- a/apex/Android.bp
+++ b/apex/Android.bp
@@ -80,9 +80,8 @@
     },
 }
 
-prebuilt_etc {
+linker_config {
     name: "bionic-linker-config",
-    src: "linker.config.txt",
-    filename: "linker.config.txt",
+    src: "linker.config.json",
     installable: false,
 }