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/mvebu_mcbin-88f8040_defconfig b/configs/mvebu_mcbin-88f8040_defconfig
index e8095d4..60d3940 100644
--- a/configs/mvebu_mcbin-88f8040_defconfig
+++ b/configs/mvebu_mcbin-88f8040_defconfig
@@ -23,6 +23,7 @@
 CONFIG_DISPLAY_BOARDINFO_LATE=y
 CONFIG_ARCH_EARLY_INIT_R=y
 CONFIG_BOARD_EARLY_INIT_F=y
+CONFIG_SYS_MAXARGS=32
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_MMC=y