mx6cuboxi: Move CONFIG_CMD_SATA to Kconfig

Move CONFIG_CMD_SATA option to Kconfig to fix the following build
error:

In file included from include/configs/mx6cuboxi.h:137:0,
                 from include/config.h:7,
                 from include/common.h:21,
                 from common/env_common.c:11:
include/config_distro_bootcmd.h:161:2: error: expected '}' before 'BOOT_TARGET_DEVICES_references_SATA_without_CONFIG_SATA'
  BOOT_TARGET_DEVICES_references_SATA_without_CONFIG_SATA

Reported-by: Stefano Babic <sbabic@denx.de>
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>