Refactor device padding to be set per grid option

- Fixes bug where devices with scaled grids were not
  getting the correct deivce padding.
- Also fix bug where device padding was invalid.
  Added validation check when processing paddings to prevent
  this from happening again.

Bug: 175329686
Test: manual, enable debug flag,
      run and verify no crash from validation check

Change-Id: I35b019c40667c08de4fad95ac4b05b2d8f8a0e74