drm/i915: Update init_context() to take a request structure

Now that everything above has been converted to use requests, it is possible to
update init_context() to take a request pointer instead of a ring/context pair.

For: VIZ-5115
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Tomas Elf <tomas.elf@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 73db3ae..2bf58fa 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -176,8 +176,7 @@
 
 	int		(*init_hw)(struct intel_engine_cs *ring);
 
-	int		(*init_context)(struct intel_engine_cs *ring,
-					struct intel_context *ctx);
+	int		(*init_context)(struct drm_i915_gem_request *req);
 
 	void		(*write_tail)(struct intel_engine_cs *ring,
 				      u32 value);