drm/amd/display: setup system context for APUs

commit 3ca001a upstream.

Scatter/gather is APU feature starting from carrizo.
adev->apu_flags is not used for all APUs.
adev->flags & AMD_IS_APU can be used for all APUs.

Signed-off-by: Aaron Liu <aaron.liu@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

@@ -1202,7 +1202,7 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
 	dc_hardware_init(adev->dm.dc);
 
 #if defined(CONFIG_DRM_AMD_DC_DCN)
-	if (adev->apu_flags) {
+	if ((adev->flags & AMD_IS_APU) && (adev->asic_type >= CHIP_CARRIZO)) {
 		struct dc_phy_addr_space_config pa_config;
 
 		mmhub_read_system_context(adev, &pa_config);