powerpc/cacheinfo: Rename cache_dir per-cpu variable

The per_cpu__ prefix on DECLARE_PER_CPU'd variables is going away;
rename cache_dir to cache_dir_pcpu.

Signed-off-by: Nathan Lynch <ntl@pobox.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
1 file changed