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/smartweb_defconfig b/configs/smartweb_defconfig
index 3cf30dd..af848d1 100644
--- a/configs/smartweb_defconfig
+++ b/configs/smartweb_defconfig
@@ -38,6 +38,7 @@
 CONFIG_SPL_NAND_BASE=y
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="U-Boot# "
+CONFIG_SYS_MAXARGS=32
 # CONFIG_CMD_IMI is not set
 CONFIG_CMD_DFU=y
 # CONFIG_CMD_LOADS is not set