STM32WB55RG: temporarily remove device_name property in targets.json

Until the CMSIS pack device name is officially deployed.

then we'll the name as can be found in Keil CMSIS pack

       <!-- *************************  Device 'STM32WB55RG'  ***************************** -->
        <device Dname="STM32WB55RGVx">
          <memory id="IROM1"                           start="0x08000000" size="0x001000000" startup="1" default="1" />
          <memory id="IRAM1"                           start="0x20000000" size="0x000040000" init="0"    default="1" />
          <algorithm name="CMSIS/Flash/STM32WB_M4.FLM" start="0x08000000" size="0x001000000"             default="1" />

          <feature type="QFP" n="68"/>
        </device>

Author: LMESTM

targets/targets.json

@@ -7702,7 +7702,6 @@
 		],
         "features": ["BLE"],
         "release_versions": ["2", "5"],
-        "device_name": "STM32WB55RG",
         "bootloader_supported": true
     },
     "VBLUNO52": {