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/tec-ng_defconfig b/configs/tec-ng_defconfig
index ea568d4..29dda19 100644
--- a/configs/tec-ng_defconfig
+++ b/configs/tec-ng_defconfig
@@ -15,6 +15,7 @@
 CONFIG_CONSOLE_MUX=y
 CONFIG_SYS_STDIO_DEREGISTER=y
 CONFIG_SYS_PROMPT="Tegra30 (TEC-NG) # "
+CONFIG_SYS_MAXARGS=64
 # CONFIG_CMD_IMI is not set
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_I2C=y