Convert CONFIG_SYS_MAXARGS to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_MAXARGS

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/colibri-imx6ull-emmc_defconfig b/configs/colibri-imx6ull-emmc_defconfig
index eb4b6a7..fb33c57 100644
--- a/configs/colibri-imx6ull-emmc_defconfig
+++ b/configs/colibri-imx6ull-emmc_defconfig
@@ -21,6 +21,7 @@
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_DISPLAY_BOARDINFO_LATE=y
 CONFIG_SYS_PROMPT="Colibri iMX6ULL # "
+CONFIG_SYS_MAXARGS=32
 # CONFIG_BOOTM_PLAN9 is not set
 # CONFIG_BOOTM_RTEMS is not set
 # CONFIG_CMD_ELF is not set