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/imx8mp_dhcom_pdk2_defconfig b/configs/imx8mp_dhcom_pdk2_defconfig
index 2764152..5118147 100644
--- a/configs/imx8mp_dhcom_pdk2_defconfig
+++ b/configs/imx8mp_dhcom_pdk2_defconfig
@@ -54,6 +54,7 @@
 CONFIG_SPL_WATCHDOG=y
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="u-boot=> "
+CONFIG_SYS_MAXARGS=64
 # CONFIG_BOOTM_NETBSD is not set
 # CONFIG_BOOTM_PLAN9 is not set
 # CONFIG_BOOTM_RTEMS is not set