drm/amd/display: call amdgpu_dm_fini when hw_fini.

to free up drm mode_config info.

fix issue: unload amdgpu, can't load amdgpu again.
[drm:drm_debugfs_init [drm]] *ERROR* Cannot create /sys/kernel/debug/dri/0
[drm:drm_minor_register [drm]] *ERROR* DRM: Failed to initialize /sys/kernel/debug/dri.

Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Andrey Grodzovsky<andrey.grodzovsky@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -395,9 +395,8 @@ void amdgpu_dm_fini(struct amdgpu_device *adev)
 		adev->dm.freesync_module = NULL;
 	}
 	/* DC Destroy TODO: Replace destroy DAL */
-	{
+	if (adev->dm.dc)
 		dc_destroy(&adev->dm.dc);
-	}
 	return;
 }
 
@@ -490,7 +489,7 @@ static int dm_hw_fini(void *handle)
 	amdgpu_dm_hpd_fini(adev);
 
 	amdgpu_dm_irq_fini(adev);
-
+	amdgpu_dm_fini(adev);
 	return 0;
 }
 

drivers/gpu/drm/amd/display/dc/core/dc.c

@@ -1541,7 +1541,12 @@ enum dc_irq_source dc_interrupt_to_irq_source(
 
 void dc_interrupt_set(const struct dc *dc, enum dc_irq_source src, bool enable)
 {
-	struct core_dc *core_dc = DC_TO_CORE(dc);
+	struct core_dc *core_dc;
+
+	if (dc == NULL)
+		return;
+	core_dc = DC_TO_CORE(dc);
+
 	dal_irq_service_set(core_dc->res_pool->irqs, src, enable);
 }