ANDROID: KVM: arm64: iommu: Allocate IDMAPPED domain from the driver

There is no reason why the IOMMU code would allocate this domain.
EL1 can just allocate it, this helps decoupling atomic_mc and the
IDMAPPED domains in EL2 for drivers that don't want to opt in the
domain management.

Bug: 277989609
Bug: 278749606
Bug: 346441377

Change-Id: I1620bb3ad36e6a3948e19757b5dcf619a3cc63e5
Signed-off-by: Mostafa Saleh <smostafa@google.com>