ARM: s3c6400_defconfig: enable more boards in defconfig

This enables all of s3c64xx boards in the s3c6400_defconfig.
In this time, MINI6410, REAL6410, and WLF_CRAGG_6410 are
added in the defconfig.

Cc: Darius Augulis <augulis.darius@gmail.com>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>