drm/i915: Resurrect golden context on gen6/7

In

commit 8f0e2b9d95a88ca5d8349deef2375644faf184ae
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Tue Dec 2 16:19:07 2014 +0100

    drm/i915: Move golden context init into ->init_context

I've shuffled around per-ctx init code a bit for legacy contexts but
accidentally dropped the render state init call on gen6/7. Resurrect
it.

Reported-by: Francisco Jerez <currojerez@riseup.net>
Cc: Francisco Jerez <currojerez@riseup.net>
Cc: Dave Gordon <david.s.gordon@intel.com>
Cc: Thomas Daniel <thomas.daniel@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -2623,6 +2623,7 @@ int intel_init_render_ring_buffer(struct drm_device *dev)
 			GEN8_RING_SEMAPHORE_INIT;
 		}
 	} else if (INTEL_INFO(dev)->gen >= 6) {
+		ring->init_context = i915_gem_render_state_init;
 		ring->add_request = gen6_add_request;
 		ring->flush = gen7_render_ring_flush;
 		if (INTEL_INFO(dev)->gen == 6)