fix null device reference
fix null device reference

Summary:
Force device type from BaseDevice to AndroidDevice, because we need to access adb inside AndroidDevice.
In long term, we should use DeviceShell from BaseDevice, but that need much more changes.

Differential Revision: D8876082

fbshipit-source-id: 0772a0ac361c5e3eca9c7a590281ffa786501e15

facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper