target-ppc: Split out SREGS get/put functions

target-ppc: Split out SREGS get/put functions

Currently the getting and setting of Power MMU registers (sregs) take up
large inline chunks of the kvm_arch_get_registers() and
kvm_arch_put_registers() functions.  Especially since there are two
variants (for Book-E and Book-S CPUs), only one of which will be used in
practice, this is pretty hard to read.

This patch splits these out into helper functions for clarity.  No
functional change is expected.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Greg Kurz <gkurz@linux.vnet.ibm.com>