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/ls1088aqds_sdcard_qspi_defconfig b/configs/ls1088aqds_sdcard_qspi_defconfig
index 0c7a465..07ded3f 100644
--- a/configs/ls1088aqds_sdcard_qspi_defconfig
+++ b/configs/ls1088aqds_sdcard_qspi_defconfig
@@ -45,6 +45,7 @@
 CONFIG_SPL_ENV_SUPPORT=y
 CONFIG_SPL_I2C=y
 CONFIG_SPL_MPC8XXX_INIT_DDR=y
+CONFIG_SYS_MAXARGS=64
 CONFIG_CMD_GREPENV=y
 CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS=5
 CONFIG_CMD_MEMINFO=y