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/r8a77995_draak_defconfig b/configs/r8a77995_draak_defconfig
index 0082547..1c5536a 100644
--- a/configs/r8a77995_draak_defconfig
+++ b/configs/r8a77995_draak_defconfig
@@ -23,6 +23,7 @@
 CONFIG_DEFAULT_FDT_FILE="r8a77995-draak.dtb"
 CONFIG_UPDATE_TFTP=y
 CONFIG_HUSH_PARSER=y
+CONFIG_SYS_MAXARGS=64
 CONFIG_CMD_BOOTZ=y
 CONFIG_CMD_DFU=y
 CONFIG_CMD_GPIO=y