drm/amdgpu: Fix create_dmamap_sg_bo kdoc warnings

Fix the following gcc with W=1:

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:292: warning: Cannot understand  * @create_dmamap_sg_bo: Creates a amdgpu_bo object to reflect information

Cc: Felix Kuehling <felix.kuehling@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -290,8 +290,9 @@ void amdgpu_amdkfd_release_notify(struct amdgpu_bo *bo)
 }
 
 /**
- * @create_dmamap_sg_bo: Creates a amdgpu_bo object to reflect information
+ * create_dmamap_sg_bo() - Creates a amdgpu_bo object to reflect information
  * about USERPTR or DOOREBELL or MMIO BO.
+ *
  * @adev: Device for which dmamap BO is being created
  * @mem: BO of peer device that is being DMA mapped. Provides parameters
  *	 in building the dmamap BO