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/ev-imx280-nano-x-mb_defconfig b/configs/ev-imx280-nano-x-mb_defconfig
index 770f05f..8649338 100644
--- a/configs/ev-imx280-nano-x-mb_defconfig
+++ b/configs/ev-imx280-nano-x-mb_defconfig
@@ -8,6 +8,7 @@
 CONFIG_EV_IMX280_NANO_X_MB=y
 CONFIG_IMX_MODULE_FUSE=y
 CONFIG_HUSH_PARSER=y
+CONFIG_SYS_MAXARGS=32
 CONFIG_CMD_BOOTZ=y
 CONFIG_CMD_MEMINFO=y
 CONFIG_CMD_MEMTEST=y