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/brsmarc1_defconfig b/configs/brsmarc1_defconfig
index 1eef3bd..29c54fc 100644
--- a/configs/brsmarc1_defconfig
+++ b/configs/brsmarc1_defconfig
@@ -44,6 +44,7 @@
 CONFIG_SYS_SPI_U_BOOT_OFFS=0x40000
 CONFIG_SPL_YMODEM_SUPPORT=y
 CONFIG_HUSH_PARSER=y
+CONFIG_SYS_MAXARGS=64
 # CONFIG_CMD_BOOTD is not set
 CONFIG_CMD_BOOTZ=y
 # CONFIG_BOOTM_NETBSD is not set