To make the x86 page table base implementation compatible with the
function signatures used in hw, make the Intel IOMMU specific arguments
optional:
- Make the `flush` parameter default to false.
- Make the `supported_sizes` parameter default to 1GB + 2MB + 4k.
Issue #5217
On hw, `Page_flags` is used throughout architectures. At the same time,
it is used by the Intel IOMMU page table implementation in the pc
platform driver.
Consolidate the definition in base so it is available for all users.
Issue #5217
