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/guruplug_defconfig b/configs/guruplug_defconfig
index 89d78cf..57d66c6 100644
--- a/configs/guruplug_defconfig
+++ b/configs/guruplug_defconfig
@@ -22,6 +22,7 @@
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_RESET_PHY_R=y
 CONFIG_HUSH_PARSER=y
+CONFIG_SYS_MAXARGS=32
 CONFIG_CMD_BOOTZ=y
 # CONFIG_CMD_FLASH is not set
 CONFIG_CMD_IDE=y