drm/i915: dump UTS_RELEASE into the error_state

commit 4518f611ba21ba165ea3714055938a8984a44ff9 upstream.

Useful for statistics or on overflowing bug reports to keep things all
lined up.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>