VK RZ A1H: remove target from mbed 2 release

As it does not share the codebase with RZ A1H, it needs to be disabled until
bring it up to date with the latest changes to cmsis. There are changes
regarding caches, mmu and others

targets/targets.json

@@ -2411,7 +2411,7 @@
         "device_has": ["ANALOGIN", "CAN", "ETHERNET", "I2C", "I2CSLAVE", "INTERRUPTIN", "PORTIN", "PORTINOUT", "PORTOUT", "PWMOUT", "RTC", "SERIAL", "SERIAL_FC", "SPI", "SPISLAVE", "STDIO_MESSAGES"],
         "features": ["LWIP"],
         "default_lib": "std",
-        "release_versions": ["2"]
+        "release_versions": []
     },
     "MAXWSNENV": {
         "inherits": ["Target"],