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/mx6memcal_defconfig b/configs/mx6memcal_defconfig
index b218517..fb1a487 100644
--- a/configs/mx6memcal_defconfig
+++ b/configs/mx6memcal_defconfig
@@ -18,6 +18,7 @@
 CONFIG_SPL_USB_HOST=y
 CONFIG_SPL_WATCHDOG=y
 CONFIG_HUSH_PARSER=y
+CONFIG_SYS_MAXARGS=32
 # CONFIG_CMD_BOOTD is not set
 # CONFIG_CMD_BOOTM is not set
 # CONFIG_CMD_ELF is not set