xtensa: make MMU-related configuration options depend on MMU
xtensa: make MMU-related configuration options depend on MMU

MMUv3 and HIGHMEM support are available only on configurations with MMU,
don't show them otherwise.

Signed-off-by: Max Filippov <8c5ea195856807f4f02a6e0749c87ea6b7375f38@gmail.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs