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/cm_t43_defconfig b/configs/cm_t43_defconfig
index 7a0cd52..0a64d1d 100644
--- a/configs/cm_t43_defconfig
+++ b/configs/cm_t43_defconfig
@@ -40,6 +40,7 @@
 CONFIG_SPL_SPI_LOAD=y
 CONFIG_SYS_SPI_U_BOOT_OFFS=0x40000
 CONFIG_SYS_PROMPT="CM-T43 # "
+CONFIG_SYS_MAXARGS=64
 CONFIG_CMD_ASKENV=y
 CONFIG_CMD_EEPROM=y
 CONFIG_CMD_EEPROM_LAYOUT=y