schemas: legacy: add G751 device

Description
Add G751 to TempSensor types enum.

Motivation
Need to use the G751 device to monitor the temperature.

Change-Id: Ia1b7f3208ba3ef6de646b3a74ca6e286ce5919ac
Signed-off-by: Andy Hsu <andy.hsu.wiwynn@gmail.com>
diff --git a/schemas/legacy.json b/schemas/legacy.json
index 447aa9d..cdc4db1 100644
--- a/schemas/legacy.json
+++ b/schemas/legacy.json
@@ -692,6 +692,7 @@
                         "EMC1412",
                         "EMC1413",
                         "EMC1414",
+                        "G751",
                         "HDC1080",
                         "JC42",
                         "LM75A",