Inside the error capture itself, we refer to not only the hardware
engine, its ringbuffer but also the capture state. Finding clear names
for each whilst avoiding mixing ring/intel_engine_cs is tricky. As a
compromise we keep using ering for the error capture.

v2: Use 'ee' locals for struct drm_i915_error_engine
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1469432687-22756-8-git-send-email-chris@chris-wilson.co.uk
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469606850-28659-3-git-send-email-chris@chris-wilson.co.uk