drm/amdgpu: Direct ret in ras_reset_err_cnt on VF

With adding sriov_vf check, we directly return EOPNOTSUPP in
ras_reset_error_count as we should not do anything on VF to reset RAS error
count.

This also fixes the issue that loading guest driver causes register
violations.

Reviewed-by: Ahmad Rehman <Ahmad.Rehman@amd.com>
Signed-off-by: Ellen Pan <yunru.pan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>