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/netgear_dgnd3700v2_ram_defconfig b/configs/netgear_dgnd3700v2_ram_defconfig
index e1f9cee..bbfa9e1 100644
--- a/configs/netgear_dgnd3700v2_ram_defconfig
+++ b/configs/netgear_dgnd3700v2_ram_defconfig
@@ -18,6 +18,7 @@
 CONFIG_OF_STDOUT_VIA_ALIAS=y
 CONFIG_DISPLAY_CPUINFO=y
 CONFIG_BOARD_EARLY_INIT_F=y
+CONFIG_SYS_MALLOC_BOOTPARAMS=y
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="DGND3700v2 # "
 CONFIG_SYS_MAXARGS=24