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/malta64_defconfig b/configs/malta64_defconfig
index 944d0fd..cbea4fa 100644
--- a/configs/malta64_defconfig
+++ b/configs/malta64_defconfig
@@ -12,6 +12,7 @@
 # CONFIG_AUTOBOOT is not set
 CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_MISC_INIT_R=y
+CONFIG_SYS_MALLOC_BOOTPARAMS=y
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="malta # "
 CONFIG_SYS_CBSIZE=256