Switch between K64F/K66F for statistics example

Author: Deepika

tools/test/examples/examples.json

@@ -155,7 +155,7 @@
         "mbed": [],
         "test-repo-source": "github",
         "features" : [],
-        "targets" : ["K64F"],
+        "targets" : ["K66F"],
         "toolchains" : [],
         "exporters": [],
         "compile" : true,
@@ -181,7 +181,7 @@
         "mbed": [],
         "test-repo-source": "github",
         "features" : [],
-        "targets" : ["K64F"],
+        "targets" : ["K66F"],
         "toolchains" : [],
         "exporters": [],
         "compile" : true,