[Bugfix] Copy to `_sdram_current` not `&_sdram_current`
[Bugfix] Copy to `_sdram_current` not `&_sdram_current`

ctn-archive/nengo_spinnaker_2014,ctn-archive/nengo_spinnaker_2014,ctn-archive/nengo_spinnaker_2014,ctn-archive/nengo_spinnaker_2014