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/dockstar_defconfig b/configs/dockstar_defconfig
index a740da9..d591c4a 100644
--- a/configs/dockstar_defconfig
+++ b/configs/dockstar_defconfig
@@ -21,6 +21,7 @@
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="DockStar> "
+CONFIG_SYS_MAXARGS=32
 # CONFIG_CMD_FLASH is not set
 CONFIG_CMD_NAND=y
 CONFIG_CMD_USB=y