x86/mm: Clean IOMMU flags from p2m-pt code

x86/mm: Clean IOMMU flags from p2m-pt code

At this moment IOMMU pt sharing is disabled by commit [1].

This patch aims to clear the IOMMU hap share support as it will not be
used in the future. By doing this the IOMMU bits used in pte[52:58] can
be used in other ways.

[1] c2ba3db31ef2d9f1e40e7b6c16cf3be3d671d555

Suggested-by: George Dunlap <george.dunlap@citrix.com>
Signed-off-by: Alexandru Isaila <aisaila@bitdefender.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Brian Woods <brian.woods@amd.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>