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/comtrend_ar5387un_ram_defconfig b/configs/comtrend_ar5387un_ram_defconfig
index 67fa622..599fda4 100644
--- a/configs/comtrend_ar5387un_ram_defconfig
+++ b/configs/comtrend_ar5387un_ram_defconfig
@@ -17,6 +17,7 @@
 CONFIG_REMAKE_ELF=y
 CONFIG_OF_STDOUT_VIA_ALIAS=y
 CONFIG_DISPLAY_CPUINFO=y
+CONFIG_SYS_MALLOC_BOOTPARAMS=y
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="AR-5387un # "
 CONFIG_SYS_MAXARGS=24