drm/amdgpu: cleanup all virtualization detection routine

we need to move virt detection much earlier because:
1) HW team confirms us that RCC_IOV_FUNC_IDENTIFIER will always
be at DE5 (dw) mmio offset from vega10, this way there is no
need to implement detect_hw_virt() routine in each nbio/chip file.
for VI SRIOV chip (tonga & fiji), the BIF_IOV_FUNC_IDENTIFIER is at
0x1503

2) we need to acknowledged we are SRIOV VF before we do IP discovery because
the IP discovery content will be updated by host everytime after it recieved
a new coming "REQ_GPU_INIT_DATA" request from guest (there will be patches
for this new handshake soon).

Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Emily Deng <Emily.Deng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>