drm/amdgpu: set system aperture to cover whole FB region in mmhub v9.4

In XGMI configuration, the FB region covers vram region from peer
device, adjust system aperture to cover all of them
Signed-off-by: Le Ma <le.ma@amd.com>
Reviewed-by: Feifei Xu <Feifei.Xu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/mmhub_v9_4.c

@@ -114,12 +114,11 @@ static void mmhub_v9_4_init_system_aperture_regs(struct amdgpu_device *adev,
 	WREG32_SOC15_OFFSET(MMHUB, 0,
 			    mmVMSHAREDVC0_MC_VM_SYSTEM_APERTURE_LOW_ADDR,
 			    hubid * MMHUB_INSTANCE_REGISTER_OFFSET,
-			    min(adev->gmc.vram_start, adev->gmc.agp_start)
-			    >> 18);
+			    min(adev->gmc.fb_start, adev->gmc.agp_start) >> 18);
 	WREG32_SOC15_OFFSET(MMHUB, 0,
 			    mmVMSHAREDVC0_MC_VM_SYSTEM_APERTURE_HIGH_ADDR,
 			    hubid * MMHUB_INSTANCE_REGISTER_OFFSET,
-			    max(adev->gmc.vram_end, adev->gmc.agp_end) >> 18);
+			    max(adev->gmc.fb_end, adev->gmc.agp_end) >> 18);
 
 	/* Set default page address. */
 	value = adev->vram_scratch.gpu_addr - adev->gmc.vram_start +