export: fix IAR definition for dual core STM32 DISCO_H747I

Author: ABOSTM

targets/targets.json

@@ -3369,7 +3369,6 @@
             "FLASH",
             "MPU"
         ],
-        "device_name": "STM32H747XIHx",
         "bootloader_supported": true
     },
     "DISCO_H747I_CM7": {

tools/export/iar/iar_definitions.json

@@ -371,7 +371,7 @@
     "STM32H743ZI": {
         "OGChipSelectEditMenu": "STM32H743ZI\tST STM32H743ZI"
     },
-    "DISCO_H747I": {
+    "STM32H747XIHx": {
         "OGChipSelectEditMenu": "STM32H747XI_CM7\tST STM32H747XI_CM7"
     },
     "DISCO_H747I_CM4": {