Expose TargetFSConfigGen to DeviceConfig from Make

Bug: 118089258
Test: m oemaids_header_gen oemaids_headers
Change-Id: I2675822ae01af9bbec70f0c0413c047f36b5e024
diff --git a/android/config.go b/android/config.go
index 0c9f957..ed05c72 100644
--- a/android/config.go
+++ b/android/config.go
@@ -1048,3 +1048,7 @@
 func (c *config) ProductHiddenAPIStubsTest() []string {
 	return c.productVariables.ProductHiddenAPIStubsTest
 }
+
+func (c *deviceConfig) TargetFSConfigGen() *string {
+	return c.config.productVariables.TargetFSConfigGen
+}