drm - Attempt to fix radeon stride

drm - Attempt to fix radeon stride

* This is a bad hack which assumes that the stride must be 256-byte aligned
  for radeon GPUs.  This is apparently the case for odd monitor resolutions
  such as 1680x1050.  Most primary resolutions such as 1920x1080 are already
  naturally 256-byte aligned.

* Fixes the system console when used with odd resolutions.