Freescale: Remove IAR from list of supported toolchains

Having IAR with the supported_c_libs parameter missing a setting for a
IAR causes build failures during CI. Since IAR is no longer supported by
Mbed remove IAR as a supported toolchain to remove this inconsistency.

Author: harrisonmutai-arm

targets/targets.json

@@ -429,8 +429,7 @@
         "is_disk_virtual": true,
         "supported_toolchains": [
             "ARM",
-            "GCC_ARM",
-            "IAR"
+            "GCC_ARM"
         ],
         "inherits": [
             "Target"
@@ -487,8 +486,7 @@
         "is_disk_virtual": true,
         "supported_toolchains": [
             "GCC_ARM",
-            "ARM",
-            "IAR"
+            "ARM"
         ],
         "inherits": [
             "Target"
@@ -538,8 +536,7 @@
         "core": "Cortex-M4F",
         "supported_toolchains": [
             "ARM",
-            "GCC_ARM",
-            "IAR"
+            "GCC_ARM"
         ],
         "components_add": [
             "FLASHIAP"
@@ -628,8 +625,7 @@
         "core": "Cortex-M0+",
         "supported_toolchains": [
             "GCC_ARM",
-            "ARM",
-            "IAR"
+            "ARM"
         ],
         "extra_labels": [
             "Freescale",
@@ -698,8 +694,7 @@
         "core": "Cortex-M0+",
         "supported_toolchains": [
             "ARM",
-            "GCC_ARM",
-            "IAR"
+            "GCC_ARM"
         ],
         "extra_labels": [
             "Freescale",
@@ -762,8 +757,7 @@
         "core": "Cortex-M4F",
         "supported_toolchains": [
             "ARM",
-            "GCC_ARM",
-            "IAR"
+            "GCC_ARM"
         ],
         "extra_labels_add": [
             "Freescale",
@@ -1104,8 +1098,7 @@
         "core": "Cortex-M4F",
         "supported_toolchains": [
             "ARM",
-            "GCC_ARM",
-            "IAR"
+            "GCC_ARM"
         ],
         "extra_labels": [
             "Freescale",