Convert CONFIG_SYS_BOOTPARAMS_LEN to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_BOOTPARAMS_LEN

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/eb_cpu5282_defconfig b/configs/eb_cpu5282_defconfig
index 5a33e2f..d634280 100644
--- a/configs/eb_cpu5282_defconfig
+++ b/configs/eb_cpu5282_defconfig
@@ -17,6 +17,7 @@
 CONFIG_BOOTCOMMAND="printenv"
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_MISC_INIT_R=y
+CONFIG_SYS_MALLOC_BOOTPARAMS=y
 # CONFIG_AUTO_COMPLETE is not set
 CONFIG_SYS_PROMPT="\nEB+CPU5282> "
 CONFIG_SYS_CBSIZE=1024