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/seaboard_defconfig b/configs/seaboard_defconfig
index f3d3b0a..d9aecfa 100644
--- a/configs/seaboard_defconfig
+++ b/configs/seaboard_defconfig
@@ -13,6 +13,7 @@
 CONFIG_OF_SYSTEM_SETUP=y
 CONFIG_USE_PREBOOT=y
 CONFIG_SYS_PROMPT="Tegra20 (SeaBoard) # "
+CONFIG_SYS_MAXARGS=64
 # CONFIG_CMD_IMI is not set
 # CONFIG_CMD_FLASH is not set
 CONFIG_CMD_GPIO=y