PPC4xx: Move/rename ECC POST for 440EPx/GRx

Signed-off-by: Larry Johnson <lrj@acm.org>
diff --git a/post/board/lwmon5/ecc.c b/post/cpu/ppc4xx/denali_ecc.c
similarity index 100%
rename from post/board/lwmon5/ecc.c
rename to post/cpu/ppc4xx/denali_ecc.c