[Intel-gfx] Rebased tiling patches

[Chris Wilson]

Hi,
I'm in the process of playing with git send-email, so I thought it would
be useful to send my current patch set rebased against the updated 
drm-intel-next.

The first sequence of patches contain a set of error-handling fixes, 
which I hope are self-explanatory. Following those we have a few 
debugging patches and a couple of tweaks to the flushing. Finally, the 
last 4 contain the most obvious errors with fencing and my i915. Of 
particular note since last time, I've spotted that we failed to reset 
the fence should the user change the stride for the buffer.
-ickle