drm/amd/display: setup system context for APUs

[Why]
Scatter/gather is APU feature.
But in dm it is limited only to Renoir.
Now we need it for Vangogh.

[How]
Apply system context setup in dm_init to all APUs.
Signed-off-by: Roman Li <roman.li@amd.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -1093,7 +1093,7 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
 	dc_hardware_init(adev->dm.dc);
 
 #if defined(CONFIG_DRM_AMD_DC_DCN)
-	if (adev->asic_type == CHIP_RENOIR) {
+	if (adev->apu_flags) {
 		struct dc_phy_addr_space_config pa_config;
 
 		mmhub_read_system_context(adev, &pa_config);