drm/amdgpu: support key database loading for navi10

Starting from navi10, driver should send Key Database Load command
to bootloader before loading sys_drv and sos

Signed-off-by: John Clements <John.Clements@amd.com>
Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Xiaojie Yuan <xiaojie.yuan@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>