Cellpad fixes

First commit, fixes a logic error in my pull request from before :frowning:  

Second adds padhandler logic to support reporting 0 length in paddata if nothing has changed since last data retrieval

These commits allow Super Puzzle Fighter II Turbo HD Remix [NPUB30017] to at least continue as far with padhandler vs null padhandler

Also tested with padtest elfs' and scrogger HD, still function as normal