ANDROID: KVM: arm64: Remove CONFIG_KVM_IOMMU

As IOMMU modules can be out of tree. we can't rely on driver selecting
KVM_IOMMU to compile the IOMMU support, so we just compile it at all
time.

Bug: 277989609
Bug: 278749606
Change-Id: I9b64f3989f40d9715951a217265fe03e9258fe8a
Signed-off-by: Mostafa Saleh <smostafa@google.com>