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/ls1028aqds_tfa_defconfig b/configs/ls1028aqds_tfa_defconfig
index 556f77e..2f383be 100644
--- a/configs/ls1028aqds_tfa_defconfig
+++ b/configs/ls1028aqds_tfa_defconfig
@@ -31,6 +31,7 @@
 CONFIG_BOOTARGS="console=ttyS0,115200 root=/dev/ram0 earlycon=uart8250,mmio,0x21c0500 ramdisk_size=0x2000000 default_hugepagesz=2m hugepagesz=2m hugepages=256 video=1920x1080-32@60 cma=256M"
 CONFIG_MISC_INIT_R=y
 CONFIG_ID_EEPROM=y
+CONFIG_SYS_MAXARGS=64
 CONFIG_CMD_GREPENV=y
 CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS=5
 CONFIG_CMD_MEMTEST=y