Remove IAR from list of supported toolchains

Author: harrisonmutai-arm

targets/targets.json

@@ -818,8 +818,7 @@
         "core": "Cortex-M4F",
         "supported_toolchains": [
             "ARM",
-            "GCC_ARM",
-            "IAR"
+            "GCC_ARM"
         ],
         "macros": [
             "__ADUCM4050__",
@@ -873,8 +872,7 @@
         "core": "Cortex-M3",
         "supported_toolchains": [
             "ARM",
-            "GCC_ARM",
-            "IAR"
+            "GCC_ARM"
         ],
         "macros": [
             "__ADUCM3029__",