KVM: arm64: Sort the hypervisor memblocks

We will soon need to check if a Physical Address belongs to a memblock
at EL2, so make sure to sort them so this can be done efficiently.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-28-qperret@google.com