x86: tnc: Remove IGD and SDVO devices from driver model

With recent DM PCI changes to vesa_fb driver, external graphics
card does not work any more. This is because: after setting the
function disable bit, IGD and SDVO devices will disappear in the
PCI configuration space. This however creates an inconsistent state
from a driver model PCI controller point of view, as these two PCI
devices are still attached to its parent's child device list as
maintained by the driver model. Some driver model PCI APIs like
dm_pci_find_class() used in the vesa_fb driver, are referring to
the list to speed up the finding process instead of re-enumerating
the whole PCI bus, so it gets the stale cached data which is wrong.

To fix this, manually remove these two devices.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>