uml: refresh kernel config for v6.18

uml: refresh kernel config for v6.18

One interesting piece of information that has come up:

UML has come a long way with VFIO_PCI. But this functionality is
unused/disabled because the target doesn't set the PCI feature.

I think this feature could be added and the related CONFIG_VFIO
options could be selected by the kmod-vfio package.

That said, CONFIG_NO_IOMEM=y and friends will have to go.
So this can involve more work than one would expect.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>