CMD: Remove CMD_LOG, it's unused

$ git grep CMD_LOG
include/configs/kilauea.h:#define CONFIG_CMD_LOG
include/configs/lwmon5.h:#define CONFIG_CMD_LOG
include/configs/makalu.h:#define CONFIG_CMD_LOG
include/configs/quad100hd.h:#undef CONFIG_CMD_LOG
include/configs/zeus.h:#define CONFIG_CMD_LOG

Signed-off-by: Marek Vasut <marex@denx.de>
Acked-by: Anatolij Gustschin <agust@denx.de>