bootloader not support K66F, change back to K64F

Author: Qinghao Shi

tools/test/examples/examples.json

@@ -323,7 +323,7 @@
         "sub-repo-example": false,
         "subs": [],
         "features" : [],
-        "targets" : ["K66F", "NUCLEO_F429ZI", "UBLOX_EVK_ODIN_W2"],
+        "targets" : ["K64F", "NUCLEO_F429ZI", "UBLOX_EVK_ODIN_W2"],
         "toolchains" : [],
         "exporters": [],
         "compile" : true,