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/xtfpga_defconfig b/configs/xtfpga_defconfig
index ec7c563..e98af5e 100644
--- a/configs/xtfpga_defconfig
+++ b/configs/xtfpga_defconfig
@@ -15,6 +15,7 @@
 CONFIG_AUTOBOOT_PROMPT="Autobooting in %d seconds, press <SPACE> to stop\n"
 CONFIG_AUTOBOOT_STOP_STR=" "
 CONFIG_MISC_INIT_R=y
+CONFIG_SYS_MALLOC_BOOTPARAMS=y
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="U-Boot> "
 CONFIG_SYS_PBSIZE=1049