drm/amdgpu/vce4: Remove vce interrupt enable related code for sriov

Interrupt enable is contained in vce init table and this register could
not be accessed in secure ASICs, so just remove it.

Signed-off-by: Frank Min <Frank.Min@amd.com>
Signed-off-by: Xiangliang.Yu <Xiangliang.Yu@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>