drm/amdgpu: remove duplicate amdgpu_fence_process implementation

Looks like that somehow got missed while during porting the radeon changes.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

diff --cc drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
Simple merge