74xx_7xx: CPCI750: Add ECC support on esd CPCI-CPU/750 board

Add ECC support for DDR RAM for MV64360 on esd CPCI-CPU/750 board.

This patch also adds the "pldver" command to display the CPLD
revision.

Signed-off-by: Reinhard Arlt <reinhard.arlt@esd.eu>
Signed-off-by: Stefan Roese <sr@denx.de>