arm: map GICV in all domains, not just dom0.

arm: map GICV in all domains, not just dom0.

This requires that we allocate all p2m pages from domheap without a particular
dom because max pages is not setup yet so there is no allocation available to
us.

At some point we should create a separate p2m allocation (similar to x86's shadow allocation) and use that.

Also we seem to have been calling p2m_alloc_table twice for dom0.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Committed-by: Ian Campbell <ian.campbell@citrix.com>