drm/amdgpu: Remove the sriov checking and add firmware checking

Unify bare metal and sriov, and add firmware checking for
reg write and reg wait unify command.

Signed-off-by: Emily Deng <Emily.Deng@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-and-Tested-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>