STM32L5 MBED6 supported targets

NUCLEO_L552ZE_Q => MCU_STM32
DISCO_L562QE    => MCU_STM32

Author: jeromecoutant

targets/targets.json

@@ -4128,10 +4128,7 @@
         "mbed_rom_start": "0x08000000",
         "mbed_rom_size": "0x80000",
         "mbed_ram_start": "0x20000000",
-        "mbed_ram_size": "0x40000",
-        "release_versions": [
-            "5"
-        ]
+        "mbed_ram_size": "0x40000"
     },
     "DISCO_L562QE": {
         "inherits": [
@@ -4191,10 +4188,7 @@
         "mbed_rom_start": "0x08000000",
         "mbed_rom_size": "0x80000",
         "mbed_ram_start": "0x20000000",
-        "mbed_ram_size": "0x40000",
-        "release_versions": [
-            "5"
-        ]
+        "mbed_ram_size": "0x40000"
     },
     "NUCLEO_WB55RG": {
         "inherits": [