PPC: E500: Use MAS registers instead of internal TLB representation

PPC: E500: Use MAS registers instead of internal TLB representation

The natural format for e500 cores to do TLB manipulation with are the MAS
registers. Instead of converting them into some internal representation
and back again when the guest reads them, we can just keep the data
identical to the way the guest passed it to us.

The main advantage of this approach is that we're getting closer to being
able to share MMU data with KVM using shared memory, so that we don't need
to copy lots of MMU data back and forth all the time. For this to work
however, another patch is required that gets rid of the TLB union, as that
destroys our memory layout that needs to be identical with the kernel one.

Signed-off-by: Alexander Graf <agraf@suse.de>