schemas: firmware: add TDA38640AFirmware support

Add TDA38640AFirmware support to I2CVRFirmware, which enables defining
firmware metadata for TDA38640A voltage regulators.

Tested with a dummy config.

Change-Id: I8e575303d47a25d1b5b77696c3268e3f1878657a
Signed-off-by: Leo Yang <Leo-Yang@quantatw.com>
diff --git a/schemas/firmware.json b/schemas/firmware.json
index 7be83bd..3dfcdb3 100644
--- a/schemas/firmware.json
+++ b/schemas/firmware.json
@@ -53,7 +53,8 @@
                         "MP5998Firmware",
                         "MP994XFirmware",
                         "RAA22XGen2Firmware",
-                        "RAA22XGen3p5Firmware"
+                        "RAA22XGen3p5Firmware",
+                        "TDA38640AFirmware"
                     ]
                 },
                 "Bus": {