Expose TargetFSConfigGen to DeviceConfig from Make

Bug: 118089258
Test: m oemaids_header_gen oemaids_headers
Change-Id: I2675822ae01af9bbec70f0c0413c047f36b5e024
diff --git a/android/variable.go b/android/variable.go
index 16d7b13..666f29f 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -287,6 +287,8 @@
 	ProductHiddenAPIStubs       []string `json:",omitempty"`
 	ProductHiddenAPIStubsSystem []string `json:",omitempty"`
 	ProductHiddenAPIStubsTest   []string `json:",omitempty"`
+
+	TargetFSConfigGen *string `json:",omitempty"`
 }
 
 func boolPtr(v bool) *bool {