M2354: inherit PSA_V8_M devices

For `MCU_M2354`, the use of `device_has` in `targets.json` overrides the devices
present in the base target: `PSA_V8_M`. In particular, `DEVICE_TRNG` is missing
in `NU_M2354` builds as `TRNG` is a member of the `PSA_V8_M` `device_has` list.
As suggested by @ccli8, to ensure that `PSA_V8_M` devices are inherited by
derived targets, such as `MCU_M2354`, the correct syntax to use is
`device_has_add`.

Author: Abbas Bracken Ziad

targets/targets.json

@@ -6994,7 +6994,7 @@
             "tickless-from-us-ticker": true,
             "mpu-rom-end": "0x1fffffff"
         },
-        "device_has": [
+        "device_has_add": [
             "USTICKER",
             "LPTICKER",
             "RTC",