drm/i915: Tweak on-error bbaddr parsing for clarity

	/* Locate the current position in the ringbuffer and walk back

	 * to find the most recently dispatched batch buffer.

	 */

	bbaddr = 0;

	head = I915_READ_HEAD(ring) & HEAD_ADDR;

	val = (u32 *)(ring->virtual_start + head);

	val = (u32 *)(ring->virtual_start + head);

	while (--val >= (u32 *)ring->virtual_start) {

		bbaddr = i915_get_bbaddr(dev, val);

		if (bbaddr)

			break;

			return bbaddr;

	}

	if (bbaddr == 0) {

	val = (u32 *)(ring->virtual_start + ring->size);

	while (--val >= (u32 *)ring->virtual_start) {

		bbaddr = i915_get_bbaddr(dev, val);

		if (bbaddr)

				break;

		}

			return bbaddr;

	}

	return bbaddr;

	return 0;

}

static u32 capture_bo_list(struct drm_i915_error_buffer *err,