pc-dimm: assign and verify the "addr" property during pre_plug

pc-dimm: assign and verify the "addr" property during pre_plug

We can assign and verify the address before realizing and trying to plug.
reading/writing the address property should never fail for DIMMs, so let's
reduce error handling a bit by using &error_abort. Getting access to the
memory region now might however fail. So forward errors from
get_memory_region() properly.

As all memory devices should use the alignment of the underlying memory
region for guest physical address asignment, do detection of the
alignment in pc_dimm_pre_plug(), but allow pc.c to overwrite the
alignment for compatibility handling.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20180801133444.11269-5-david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>