WISE_1570: use hex as output

Fixes #6252. Use hex rather than binary - use the hex format validation.

Author: 0xc0170

targets/targets.json

@@ -1629,7 +1629,8 @@
         "macros_add": ["MBEDTLS_CONFIG_HW_SUPPORT", "WISE_1570", "TWO_RAM_REGIONS"],
         "device_has_add": ["ANALOGOUT", "LOWPOWERTIMER", "SERIAL_ASYNCH", "SERIAL_FC", "TRNG", "FLASH"],
         "release_versions": ["5"],
-        "device_name": "STM32L486RG"
+        "device_name": "STM32L486RG",
+        "OUTPUT_EXT": "hex"
     },
     "ARCH_MAX": {
         "inherits": ["FAMILY_STM32"],