iommu/ipmmu-vmsa: Add light version of Linux's ipmmu_features

iommu/ipmmu-vmsa: Add light version of Linux's ipmmu_features

This is a prereq work needed to add support for S4 series easily
in the future.

We don't need to pull the whole struct and all instances as Xen
driver doesn't support old Arm32 based Gen2 SoCs, so there is no
point in keeping all differences between Gen2 and Gen3 here.
All what we need is a minimal support to be able to operate with
Gen3 and new S4.

Add Gen3 specific info with only two fields (number_of_contexts and
num_utlbs) for now, the subsequent patches will add remaining bits.

No change in behavior.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Acked-by: Julien Grall <jgrall@amazon.com>