drm/amdgpu: remove job parameter from amdgpu_fence_emit()

What we actually care about is the amdgpu_fence object
so pass that in explicitly to avoid possible mistakes
in the future.

The job_run_counter handling can be safely removed at this
point as we no longer support job resubmission.

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