uboot-imx

Fix/enhance ECC POST for 440EPx/GRx

This patch allows the ECC POST to be used for different boards with the
PPC440 Denali SDRAM controller.  Modifications include skipping the test
if ECC is not enabled (as for non-ECC DIMMs) and adding synchronization
to prevent timing errors.

Signed-off-by: Larry Johnson <lrj@acm.org>