UBUNTU: [Config] enable Intel DMA remapping options by default

UBUNTU: [Config] enable Intel DMA remapping options by default

Starting with the following commit, upstream kernel is enabling Intel
IOMMU related options by default:

 792fb43ce2c9 ("iommu/vt-d: Enable Intel IOMMU scalable mode by default")

We should follow upstream direction enabling
CONFIG_INTEL_IOMMU_DEFAULT_ON and
CONFIG_INTEL_IOMMU_SCALABLE_MODE_DEFAULT_ON.

A downside is that this change may introduce boot regressions on old
systems (especially those with buggy firmware).

BugLink: https://bugs.launchpad.net/bugs/1951440
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>