arm: mvebu: Display ECC enabled / disabled upon bootup

This patch adds "(ECC enabled)" or "(ECC disabled)" to the DRAM
bootup text. Making it easier for board with SPD DIMM's to see,
if ECC is enabled or not.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Luka Perkov <luka.perkov@sartura.hr>