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/ls1043aqds_sdcard_ifc_defconfig b/configs/ls1043aqds_sdcard_ifc_defconfig
index 699ac5b..4a6d32d 100644
--- a/configs/ls1043aqds_sdcard_ifc_defconfig
+++ b/configs/ls1043aqds_sdcard_ifc_defconfig
@@ -53,6 +53,7 @@
 CONFIG_SPL_I2C=y
 CONFIG_SPL_MPC8XXX_INIT_DDR=y
 CONFIG_SPL_WATCHDOG=y
+CONFIG_SYS_MAXARGS=64
 CONFIG_CMD_BOOTZ=y
 CONFIG_CMD_IMLS=y
 CONFIG_CMD_GREPENV=y