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/omap4_sdp4430_defconfig b/configs/omap4_sdp4430_defconfig
index 9dae340..6185421 100644
--- a/configs/omap4_sdp4430_defconfig
+++ b/configs/omap4_sdp4430_defconfig
@@ -17,6 +17,7 @@
 CONFIG_SYS_CONSOLE_INFO_QUIET=y
 # CONFIG_SPL_I2C is not set
 # CONFIG_SPL_NAND_SUPPORT is not set
+CONFIG_SYS_MAXARGS=64
 CONFIG_CMD_ASKENV=y
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_I2C=y