powerpc/configs: Add missing config symbols for ppc64_defconfig

This patch adds missing config symbols for ppc64_defconfig
to enable cgroups, memhotplug, numa balancing and XFS
in core kernel image.

Signed-off-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>