On the ppc 4xx architecture the instruction cache must be flushed as
well as the data cache.  This patch just makes it generic for all
architectures where CACHE_FLUSH_IS_SAFE is set to 1.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>