drm/i915: rename 'ring' where it refers to an engine or engine_id

'ring' is an old deprecated term for a GPU engine. Chris Wilson wants to
use the name for what is currently known as an intel_ringbuffer, but it
will be dreadfully confusing if some rings are ringbuffers but other
rings are still engines. So this patch changes the names of a bunch of
parameters called 'ring' to either 'engine' or 'engine_id' according to
what they actually are.

Signed-off-by: Dave Gordon <david.s.gordon@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469034967-15840-3-git-send-email-david.s.gordon@intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/intel_mocs.h b/drivers/gpu/drm/i915/intel_mocs.h
index 4640299..a8bd9f7 100644
--- a/drivers/gpu/drm/i915/intel_mocs.h
+++ b/drivers/gpu/drm/i915/intel_mocs.h
@@ -54,6 +54,6 @@
 
 int intel_rcs_context_init_mocs(struct drm_i915_gem_request *req);
 void intel_mocs_init_l3cc_table(struct drm_device *dev);
-int intel_mocs_init_engine(struct intel_engine_cs *ring);
+int intel_mocs_init_engine(struct intel_engine_cs *engine);
 
 #endif