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/khadas-vim3l_defconfig b/configs/khadas-vim3l_defconfig
index 2e1eabc..506df51 100644
--- a/configs/khadas-vim3l_defconfig
+++ b/configs/khadas-vim3l_defconfig
@@ -16,6 +16,7 @@
 CONFIG_OF_BOARD_SETUP=y
 # CONFIG_DISPLAY_CPUINFO is not set
 CONFIG_MISC_INIT_R=y
+CONFIG_SYS_MAXARGS=32
 # CONFIG_CMD_BDI is not set
 # CONFIG_CMD_IMI is not set
 CONFIG_CMD_GPIO=y