Remove support for 802.15.4 PHY from KW24D as it is connected using SPI within the SoC

Author: Donatien Garnier

targets/targets.json

@@ -1266,8 +1266,7 @@
             "SLEEP",
             "STDIO_MESSAGES",
             "TRNG",
-            "FLASH",
-            "802_15_4_PHY"
+            "FLASH"
         ],
         "release_versions": ["2", "5"],
         "device_name": "MKW24D512xxx5",