SurfaceFlinger: add a backdoor to override display config

To generate a config change (and override all other config changes):
    adb shell service call SurfaceFlinger 1035 i32 <config_id>
To disable backdoor override:
    adb shell service call SurfaceFlinger 1035 i32 -1

Test: change configs from backdoor
Fixes: 130044117
Change-Id: Iab5a4ca4866139946ca3f8a6ac78fa9e13fe6d00