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/ap121_defconfig b/configs/ap121_defconfig
index 0baa4c8..648cf22 100644
--- a/configs/ap121_defconfig
+++ b/configs/ap121_defconfig
@@ -20,6 +20,7 @@
 CONFIG_BOOTCOMMAND="sf probe;mtdparts default;bootm 0x9f650000"
 CONFIG_DISPLAY_CPUINFO=y
 CONFIG_BOARD_EARLY_INIT_F=y
+CONFIG_SYS_MALLOC_BOOTPARAMS=y
 CONFIG_SYS_PROMPT="ap121 # "
 CONFIG_SYS_CBSIZE=256
 CONFIG_SYS_PBSIZE=281