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/ls1021aqds_sdcard_qspi_defconfig b/configs/ls1021aqds_sdcard_qspi_defconfig
index 62100e4..318f4f5 100644
--- a/configs/ls1021aqds_sdcard_qspi_defconfig
+++ b/configs/ls1021aqds_sdcard_qspi_defconfig
@@ -41,6 +41,8 @@
 CONFIG_ID_EEPROM=y
 CONFIG_SPL_MAX_SIZE=0x1a000
 CONFIG_SPL_PAD_TO=0x1c000
+CONFIG_SPL_HAS_BSS_LINKER_SECTION=y
+CONFIG_SPL_BSS_START_ADDR=0x80100000
 CONFIG_SPL_BSS_MAX_SIZE=0x80000
 CONFIG_SPL_FSL_PBL=y
 # CONFIG_SPL_SHARES_INIT_SP_ADDR is not set