drm/amdgpu: don't enable secure display on incompatible platforms

[why]
[drm] psp gfx command LOAD_TA(0x1) failed and response status is (0x7)
[drm] psp gfx command INVOKE_CMD(0x3) failed and response status is (0x4)
amdgpu 0000:04:00.0: amdgpu: Secure display: Generic Failure.

[how]
don't enable secure display on incompatible platforms

Suggested-by: Aaron Liu <aaron.liu@amd.com>
Signed-off-by: Jesse zhang <jesse.zhang@amd.com>
Reviewed-by: Aaron Liu <aaron.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>