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/M5249EVB_defconfig b/configs/M5249EVB_defconfig
index 65606c4..171df12 100644
--- a/configs/M5249EVB_defconfig
+++ b/configs/M5249EVB_defconfig
@@ -13,6 +13,7 @@
 CONFIG_SYS_CONSOLE_INFO_QUIET=y
 CONFIG_SYS_DEVICE_NULLDEV=y
 # CONFIG_DISPLAY_BOARDINFO is not set
+CONFIG_SYS_MALLOC_BOOTPARAMS=y
 # CONFIG_CMDLINE_EDITING is not set
 CONFIG_SYS_PBSIZE=276
 CONFIG_CMD_IMLS=y