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/ls1046aqds_lpuart_defconfig b/configs/ls1046aqds_lpuart_defconfig
index d153882..60685c5 100644
--- a/configs/ls1046aqds_lpuart_defconfig
+++ b/configs/ls1046aqds_lpuart_defconfig
@@ -36,6 +36,7 @@
 CONFIG_BOOTCOMMAND="run distro_bootcmd; run nor_bootcmd; env exists secureboot && esbc_halt;;"
 CONFIG_ARCH_MISC_INIT=y
 CONFIG_MISC_INIT_R=y
+CONFIG_SYS_MAXARGS=64
 CONFIG_CMD_BOOTZ=y
 CONFIG_CMD_IMLS=y
 CONFIG_CMD_GREPENV=y