STM32F7 MBED6 supported targets

DISCO_F746NG  => MCU_STM32
NUCLEO_F746ZG => MCU_STM32
NUCLEO_F756ZG => MCU_STM32
NUCLEO_F767ZI => MCU_STM32
DISCO_F769NI  => MCU_STM32

Author: jeromecoutant

targets/targets.json

@@ -2515,10 +2515,6 @@
             "USBDEVICE",
             "MPU"
         ],
-        "release_versions": [
-            "2",
-            "5"
-        ],
         "device_name": "STM32F746NG",
         "bootloader_supported": true,
         "overrides": {
@@ -2574,10 +2570,6 @@
             "USBDEVICE",
             "MPU"
         ],
-        "release_versions": [
-            "2",
-            "5"
-        ],
         "device_name": "STM32F746ZG",
         "bootloader_supported": true,
         "overrides": {
@@ -2634,10 +2626,6 @@
             "USBDEVICE",
             "MPU"
         ],
-        "release_versions": [
-            "2",
-            "5"
-        ],
         "device_name": "STM32F756ZG",
         "overrides": {
             "lpticker_delay_ticks": 0,
@@ -2691,9 +2679,6 @@
         "features": [
             "LWIP"
         ],
-        "release_versions": [
-            "5"
-        ],
         "device_name": "STM32F767VI",
         "bootloader_supported": true
     },
@@ -2752,10 +2737,6 @@
             "USBDEVICE",
             "MPU"
         ],
-        "release_versions": [
-            "2",
-            "5"
-        ],
         "device_name": "STM32F767ZI",
         "bootloader_supported": true,
         "overrides": {
@@ -2816,10 +2797,6 @@
             "QSPI"
         ],
         "bootloader_supported": true,
-        "release_versions": [
-            "2",
-            "5"
-        ],
         "device_name": "STM32F769NI",
         "overrides": {
             "lpticker_delay_ticks": 0,