drm/amdgpu: use vm_update_mode=0 as default in sriov for gfx10.3 onwards

Apply this rule to all newer asics in sriov case.
For asic with VF MMIO access protection avoid using CPU for VM table updates.
CPU pagetable updates have issues with HDP flush as VF MMIO access protection
blocks write to BIF_BX_DEV0_EPF0_VF0_HDP_MEM_COHERENCY_FLUSH_CNTL register
during sriov runtime.
Moved the check to amdgpu_device_init() to ensure it is done after
amdgpu_device_ip_early_init() where the IP versions are discovered.

Signed-off-by: Danijel Slivka <danijel.slivka@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>