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_tfa_defconfig b/configs/ls1043aqds_tfa_defconfig
index 031b5d8..37cdeeb 100644
--- a/configs/ls1043aqds_tfa_defconfig
+++ b/configs/ls1043aqds_tfa_defconfig
@@ -38,6 +38,7 @@
 # CONFIG_USE_BOOTCOMMAND is not set
 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