Convert CONFIG_SPL_BSS_START_ADDR to Kconfig

This converts the following to Kconfig:
   CONFIG_SPL_BSS_START_ADDR

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/lion-rk3368_defconfig b/configs/lion-rk3368_defconfig
index c700115..1b148f5 100644
--- a/configs/lion-rk3368_defconfig
+++ b/configs/lion-rk3368_defconfig
@@ -34,6 +34,8 @@
 CONFIG_ARCH_EARLY_INIT_R=y
 CONFIG_SPL_MAX_SIZE=0x40000
 CONFIG_SPL_PAD_TO=0x7f8000
+CONFIG_SPL_HAS_BSS_LINKER_SECTION=y
+CONFIG_SPL_BSS_START_ADDR=0x400000
 CONFIG_SPL_BSS_MAX_SIZE=0x20000
 CONFIG_SPL_BOOTROM_SUPPORT=y
 # CONFIG_SPL_RAW_IMAGE_SUPPORT is not set