drm/amdgpu: enable DCN for navi10 headless SKU

There is a NULL pointer crash when DCN disabled on headless SKU.
On normal SKU, the variable adev->ddev.mode_config.funcs is
initialized in dm_hw_init(), and it is fine to access it in
amdgpu_device_resume(). But on headless SKU, DCN is disabled,
the funcs variable is not initialized, then crash arises.
Enable DCN to fix this issue.

Reviewed-by: Alex Deucher <[e-mail]>
Reviewed-by: Guchun Chen <[e-mail]>
Signed-off-by: Tianci.Yin <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdgpu/nv.c

···
 		if (adev->enable_virtual_display || amdgpu_sriov_vf(adev))
 			amdgpu_device_ip_block_add(adev, &dce_virtual_ip_block);
 #if defined(CONFIG_DRM_AMD_DC)
-		else if (amdgpu_device_has_dc_support(adev) &&
-			 !nv_is_headless_sku(adev->pdev))
+		else if (amdgpu_device_has_dc_support(adev))
 			amdgpu_device_ip_block_add(adev, &dm_ip_block);
 #endif
 		amdgpu_device_ip_block_add(adev, &gfx_v10_0_ip_block);