Add missing IBEX define for Sonata.

sdk/boards/sonata.json

diff --git a/sdk/boards/sonata.json b/sdk/boards/sonata.json
index d6ef577..021378e 100644
--- a/sdk/boards/sonata.json
+++ b/sdk/boards/sonata.json
@@ -36,7 +36,7 @@
             "edge_triggered": true
         }
     ],
-    "defines" : "SUNBURST",
+    "defines" : ["IBEX", "SUNBURST"],
     "driver_includes" : [
         "../include/platform/sunburst",
         "../include/platform/generic-riscv"