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/socfpga_de1_soc_defconfig b/configs/socfpga_de1_soc_defconfig
index 75e16be..c2fac57 100644
--- a/configs/socfpga_de1_soc_defconfig
+++ b/configs/socfpga_de1_soc_defconfig
@@ -20,6 +20,7 @@
 CONFIG_CLOCKS=y
 # CONFIG_SPL_RAW_IMAGE_SUPPORT is not set
 CONFIG_SPL_YMODEM_SUPPORT=y
+CONFIG_SYS_MAXARGS=32
 CONFIG_CMD_ASKENV=y
 CONFIG_CMD_GREPENV=y
 # CONFIG_CMD_FLASH is not set