RZ_A1XX: public set to false as its base target

Author: 0xc0170

targets/targets.json

@@ -4745,6 +4745,7 @@
         "inherits": [
             "Target"
         ],
+        "public": false,
         "core": "Cortex-A9",
         "supported_toolchains": [
             "ARM",
@@ -7496,4 +7497,4 @@
         "version": "1",
         "public": false
     }
-}
+}