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/imx8mq_cm_defconfig b/configs/imx8mq_cm_defconfig
index 8e02460..4155a47 100644
--- a/configs/imx8mq_cm_defconfig
+++ b/configs/imx8mq_cm_defconfig
@@ -32,6 +32,7 @@
 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR=0x300
 CONFIG_SPL_I2C=y
 CONFIG_SYS_PROMPT="u-boot=> "
+CONFIG_SYS_MAXARGS=64
 CONFIG_CMD_FUSE=y
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_I2C=y