[PATCH] Fix ppc32 smp build.

[Paul Mackerras]

David Woodhouse writes:

> We make no attempt to sync the timebases on quad powersurge, as far as I
> can tell -- and we never set smp_tb_synchronized there.

Hmmm.  Does anyone still have one of those?  I have a dual but not a
quad.

In any case we can use the generic tbsync code (smp-tbsync.c) which
should work on any machine, and doesn't require any hardware support.

Paul.