drm/amdgpu/virtual_dce: Virtual display doesn't support disable vblank immediately

For virtual display, it uses software timer to emulate the vsync interrupt,
it doesn't have high precision, so doesn't support disable vblank immediately.

BUG: SWDEV-129274
Signed-off-by: Emily Deng <Emily.Deng@amd.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -221,6 +221,7 @@ int amdgpu_irq_init(struct amdgpu_device *adev)
 
 	spin_lock_init(&adev->irq.lock);
 
+	if (!adev->enable_virtual_display)
 		/* Disable vblank irqs aggressively for power-saving */
 		adev->ddev->vblank_disable_immediate = true;