weutil: add DARWIN48V platform support (#262)

Summary:
# Description

Adds initial `weutil` config for `DARWIN48V` platform. The offset for the `CHASSIS` EEPROM is not a typo: we use a smaller offset because the memory is physically smaller.

Note that this depends on the changes in #257.

Pull Request resolved: #262

Test Plan:
FBOSS OSS build passes with CentOS 9 and Linux kernel 6.4.

Validated on DARWIN48V hardware with all targets.

e.g. chassis:
```
# weutil -eeprom chassis
Version: 5
Product Name: DARWIN48V
...
CRC16: 0x1553 (CRC Matched)
```

Reviewed By: Scott8440

Differential Revision: D64087892

Pulled By: joancaneus

fbshipit-source-id: 4460f0070e233e676e7b03070f0d57925866d7dd

fboss/platform/configs/darwin48v/weutil.json

@@ -0,0 +1,17 @@
+{
+  "chassisEepromName": "CHASSIS",
+  "fruEepromList": {
+    "CHASSIS": {
+      "path": "/run/devmap/eeproms/CHASSIS_EEPROM",
+      "offset": 1536
+    },
+    "FANSPINNER": {
+      "path": "/run/devmap/eeproms/FANSPINNER_EEPROM",
+      "offset": 15360
+    },
+    "RACKMON": {
+      "path": "/run/devmap/eeproms/RACKMON_EEPROM",
+      "offset": 15360
+    }
+  }
+}