[PATCH] ppc32: add CONFIG_HZ

While ppc32 has the CONFIG_HZ Kconfig option, it wasnt actually being used.
Connect it up and set all platforms to 250Hz.  This pretty much mimics the
ppc64 patch from Anton Blanchard.

Signed-off-by: Kumar Gala <kumar.gala@freescale.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>