drm/i915/ringbuffer: Remove duplicate initialisation of ring control

int intel_init_ring_buffer(struct drm_device *dev,

			   struct intel_ring_buffer *ring)

{

	struct drm_i915_private *dev_priv = dev->dev_private;

	struct drm_i915_gem_object *obj_priv;

	struct drm_gem_object *obj;

	int ret;

	if (ret)

		goto err_unmap;

	if (!drm_core_check_feature(dev, DRIVER_MODESET))

		i915_kernel_lost_context(dev);

	else {

		ring->head = I915_READ_HEAD(ring) & HEAD_ADDR;

		ring->tail = I915_READ_TAIL(ring) & TAIL_ADDR;

		ring->space = ring->head - (ring->tail + 8);

		if (ring->space < 0)

			ring->space += ring->size;

	}

	return ret;

	return 0;

err_unmap:

	drm_core_ioremapfree(&ring->map, dev);