remove old unused board.json

boards/supermini_nrf52840.json

@@ -1,78 +0,0 @@
-{
-    "build": {
-      "arduino":{
-        "ldscript": "nrf52840_s140_v6.ld"
-      },
-      "core": "nRF5",
-      "cpu": "cortex-m4",
-      "extra_flags": "-DARDUINO_NRF52840_FEATHER -DNRF52840_XXAA",
-      "f_cpu": "64000000L",
-      "hwids": [
-        [ 
-          "0x239A",
-          "0x00B3"
-        ],
-        [
-          "0x239A",
-          "0x8029"
-        ],
-        [
-          "0x239A",
-          "0x0029"
-        ],
-        [
-          "0x239A",
-          "0x002A"
-        ],
-        [
-          "0x239A",
-          "0x802A"
-        ]
-      ],
-      "usb_product": "SuperMini nRF52840",
-      "mcu": "nrf52840",
-      "variant": "supermini_nrf52840",
-      "variants_dir": "variants",
-      "bsp": {
-        "name": "adafruit"
-      },
-      "softdevice": {
-        "sd_flags": "-DS140",
-        "sd_name": "s140",
-        "sd_version": "6.1.1",
-        "sd_fwid": "0x00B6"
-      },
-      "bootloader": {
-        "settings_addr": "0xFF000"
-      }
-    },
-    "connectivity": [
-      "bluetooth"
-    ],
-    "debug": {
-      "jlink_device": "nRF52840_xxAA",
-      "svd_path": "nrf52840.svd"
-    },
-    "frameworks": [
-      "arduino",
-      "zephyr"
-    ],
-    "name": "Nologo SuperMini nRF52840",
-    "upload": {
-      "maximum_ram_size": 248832,
-      "maximum_size": 815104,
-      "speed": 115200,
-      "protocol": "nrfutil",
-      "protocols": [
-        "jlink",
-        "nrfjprog",
-        "nrfutil",
-        "stlink"
-      ],
-      "use_1200bps_touch": true,
-      "require_upload_port": true,
-      "wait_for_upload_port": true
-    },
-    "url": "https://www.nologo.tech/en/product/otherboard/NRF52840.html",
-    "vendor": "Nologo"
-  }