drm/amdgpu: fix two documentation mismatch issues

The function name mentioned in the documentational comments mismatches
the actual one. The mismatch may make trouble for automatic documentation
generation. One of the erronous name has seen to be misused
and fixed in commit bc5ab2d2 ("drm/amdgpu: fix typo in function
sdma_v4_0_page_resume").

There is apparently no functional change in the patch.
Signed-off-by: NWang Xiayang <xywang.sjtu@sjtu.edu.cn>
Reviewed-by: NChristian König <christian.koenig@amd.com>
Reviewed-by: NHuang Rui <ray.huang@amd.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c

@@ -677,7 +677,7 @@ static uint64_t sdma_v4_0_ring_get_wptr(struct amdgpu_ring *ring)
 }
 
 /**
- * sdma_v4_0_ring_set_wptr - commit the write pointer
+ * sdma_v4_0_page_ring_set_wptr - commit the write pointer
  *
  * @ring: amdgpu ring pointer
  *
@@ -977,7 +977,7 @@ static void sdma_v4_0_page_stop(struct amdgpu_device *adev)
 }
 
 /**
- * sdma_v_0_ctx_switch_enable - stop the async dma engines context switch
+ * sdma_v4_0_ctx_switch_enable - stop the async dma engines context switch
  *
  * @adev: amdgpu_device pointer
  * @enable: enable/disable the DMA MEs context switch.