drm/i915: Remove unused ring->irq_seqno

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --cc drivers/gpu/drm/i915/i915_debugfs.c
Simple merge

diff --cc drivers/gpu/drm/i915/i915_irq.c
Simple merge

diff --cc drivers/gpu/drm/i915/intel_ringbuffer.h
Simple merge