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_db_cn9130_defconfig b/configs/mvebu_db_cn9130_defconfig
index 64f3f2f..f861108 100644
--- a/configs/mvebu_db_cn9130_defconfig
+++ b/configs/mvebu_db_cn9130_defconfig
@@ -24,6 +24,7 @@
 CONFIG_ARCH_EARLY_INIT_R=y
 CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_SYS_PROMPT="Marvell>> "
+CONFIG_SYS_MAXARGS=32
 CONFIG_CMD_I2C=y
 CONFIG_CMD_MMC=y
 CONFIG_CMD_MTD=y