Real-time 4.19 kernel rtcds has missing kernel configs

In testing the rtcds kernel for Debian 4.19, it was found that the real-time models did not have stable timing but varied by many microseconds (even beyond the loop time).
The cause appears to be that while the correct rtcds kernel patch was applied, the standard kernel config was used. We should start by using a kernel config matching the one for 4.19.67-cs in the RCG.