Add RailwayReferenceApp to gsi_car_base.mk

The app entry is missing in gsi_car_base while I4404f9800f50d16aae072ffa99fc68cad1b2482f is set to pre-install the app in tm builds, breaking gsi_car_arm64 in the process.

Fix: 233678661

Change-Id: Ica5a40b185c137cae2d7400f484772a198b80bfb
1 file changed