Convert CONFIG_SYS_BARGSIZE to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_BARGSIZE

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/eb_cpu5282_defconfig b/configs/eb_cpu5282_defconfig
index f8c0198..5a33e2f 100644
--- a/configs/eb_cpu5282_defconfig
+++ b/configs/eb_cpu5282_defconfig
@@ -7,6 +7,7 @@
 CONFIG_ENV_ADDR=0xFF040000
 CONFIG_TARGET_EB_CPU5282=y
 CONFIG_MCFTMR=y
+CONFIG_SYS_BARGSIZE=1024
 CONFIG_SYS_MONITOR_BASE=0xFF000400
 CONFIG_BOOTDELAY=5
 CONFIG_BOOT_RETRY=y