clock-hacking: disable drm debug by default
zsmalloc: HACK HACK HACK disable pgtable mapping optimization if !SMP

If you build without SMP it'll use the slow path... in fact the fast
path is not great on real SMP processors since it doesn't handle the
mapping per-cpu, but at least this fixes the build.

Not for upstream, just to fix our build if we deselect SMP (since this
seems to improve kernel performance, oddly...)