Let's move the floating point registers into a seperate subsection and
bump up the version id. This cleans up the current vmstate and will
allow for a future extension with vector registers in a compatible way.

This patch is based on a patch from Eric Farman.
Reviewed-by: NEric Farman <farman@linux.vnet.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>