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-vim2_defconfig b/configs/khadas-vim2_defconfig
index 8345e47..5e3822c 100644
--- a/configs/khadas-vim2_defconfig
+++ b/configs/khadas-vim2_defconfig
@@ -16,6 +16,7 @@
 CONFIG_CONSOLE_MUX=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_ADC=y