drm/amd/amdgpu/si_dma: Fix some function name disparity

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/amd/amdgpu/si_dma.c:320: warning: expecting prototype for cik_dma_vm_copy_pte(). Prototype was for si_dma_vm_copy_pte() instead
 drivers/gpu/drm/amd/amdgpu/si_dma.c:412: warning: expecting prototype for si_dma_pad_ib(). Prototype was for si_dma_ring_pad_ib() instead
 drivers/gpu/drm/amd/amdgpu/si_dma.c:425: warning: expecting prototype for cik_sdma_ring_emit_pipeline_sync(). Prototype was for si_dma_ring_emit_pipeline_sync() instead

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/si_dma.c

@@ -305,7 +305,7 @@ static int si_dma_ring_test_ib(struct amdgpu_ring *ring, long timeout)
 }
 
 /**
- * cik_dma_vm_copy_pte - update PTEs by copying them from the GART
+ * si_dma_vm_copy_pte - update PTEs by copying them from the GART
  *
  * @ib: indirect buffer to fill with commands
  * @pe: addr of the page entry
@@ -402,7 +402,7 @@ static void si_dma_vm_set_pte_pde(struct amdgpu_ib *ib,
 }
 
 /**
- * si_dma_pad_ib - pad the IB to the required number of dw
+ * si_dma_ring_pad_ib - pad the IB to the required number of dw
  *
  * @ring: amdgpu_ring pointer
  * @ib: indirect buffer to fill with padding
@@ -415,7 +415,7 @@ static void si_dma_ring_pad_ib(struct amdgpu_ring *ring, struct amdgpu_ib *ib)
 }
 
 /**
- * cik_sdma_ring_emit_pipeline_sync - sync the pipeline
+ * si_dma_ring_emit_pipeline_sync - sync the pipeline
  *
  * @ring: amdgpu_ring pointer
  *