arm64: defconfig: enable Layerscape EDAC driver

Most Layerscape SoCs support ECC error reporting for the memory
controller. Enable the corresponding module. In particular, this will
enable EDAC support on the Kontron sl28 board which comes with ECC
memory.

Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>