drm/amdgpu: use amdgpu_bo_create_kernel in amdgpu_ring.c

	/* Allocate ring buffer */

	if (ring->ring_obj == NULL) {

		r = amdgpu_bo_create(adev, ring->ring_size, PAGE_SIZE, true,

				     AMDGPU_GEM_DOMAIN_GTT, 0,

				     NULL, NULL, &ring->ring_obj);

		r = amdgpu_bo_create_kernel(adev, ring->ring_size, PAGE_SIZE,

					    AMDGPU_GEM_DOMAIN_GTT,

					    &ring->ring_obj,

					    &ring->gpu_addr,

					    (void **)&ring->ring);

		if (r) {

			dev_err(adev->dev, "(%d) ring create failed\n", r);

			return r;

		}

		r = amdgpu_bo_reserve(ring->ring_obj, false);

		if (unlikely(r != 0))

			return r;

		r = amdgpu_bo_pin(ring->ring_obj, AMDGPU_GEM_DOMAIN_GTT,

					&ring->gpu_addr);

		if (r) {

			amdgpu_bo_unreserve(ring->ring_obj);

			dev_err(adev->dev, "(%d) ring pin failed\n", r);

			return r;

		}

		r = amdgpu_bo_kmap(ring->ring_obj,

				       (void **)&ring->ring);

		memset((void *)ring->ring, 0, ring->ring_size);

		amdgpu_bo_unreserve(ring->ring_obj);

		if (r) {

			dev_err(adev->dev, "(%d) ring map failed\n", r);

			return r;

		}

	}

	ring->ptr_mask = (ring->ring_size / 4) - 1;

	ring->max_dw = max_dw;