PPC_OF is always selected for arch/powerpc.  This patch removes the stale
#defines
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>
Acked-by: NStephen Rothwell <sfr@canb.auug.org.au>
Acked-by: NKumar Gala <galak@kernel.crashing.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>