Include TARGET_ODM_PROP to odm/etc/build.prop

It's missing in Soong's build_prop module.

Bug: 322090587
Bug: 361623560
Test: set TARGET_ODM_PROP and see odm/etc/build.prop
Change-Id: I447a64998f6ae0ba80201ab4ab6c0fd0ef22e3e5
diff --git a/android/variable.go b/android/variable.go
index c8744ed..9026f93 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -512,6 +512,7 @@
 	SystemPropFiles    []string `json:",omitempty"`
 	SystemExtPropFiles []string `json:",omitempty"`
 	ProductPropFiles   []string `json:",omitempty"`
+	OdmPropFiles       []string `json:",omitempty"`
 
 	EnableUffdGc *string `json:",omitempty"`