Astonishing how dense I sometimes am ...
- increase the bo size so that we don't have any round-up to next tile
size areas (which the 2d blit go over, but the 1d pread/pwrite calls
will notice).
- correctly set tiling bits when copying back to a linear buffer.
- read back through a tiled bo to avoid messing with swizzling.
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>