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/controlcenterdc_defconfig b/configs/controlcenterdc_defconfig
index 9b53809..2fc7ba4 100644
--- a/configs/controlcenterdc_defconfig
+++ b/configs/controlcenterdc_defconfig
@@ -35,6 +35,8 @@
 CONFIG_BOARD_LATE_INIT=y
 CONFIG_LAST_STAGE_INIT=y
 CONFIG_SPL_MAX_SIZE=0x27fd0
+CONFIG_SPL_HAS_BSS_LINKER_SECTION=y
+CONFIG_SPL_BSS_START_ADDR=0x40028000
 CONFIG_SPL_BSS_MAX_SIZE=0x4000
 CONFIG_SPL_BOARD_INIT=y
 CONFIG_SPL_SYS_MALLOC_SIMPLE=y