powerpc/book3s64/kuap: Move Kconfig varriables to BOOK3S_64

With below two commits:
commit c91435d9 ("powerpc/book3s64/hash/kuep: Enable KUEP on hash")
commit b2ff33a1 ("powerpc/book3s64/hash/kuap: Enable kuap on hash")
the kernel now supports kuap/kuep with hash translation. Hence select the
Kconfig even when radix is disabled.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210318034829.72255-1-aneesh.kumar@linux.ibm.com